DAMASCUS, Syria -- Syria's deputy prime minister told The Associated Press that foreign fighters and their international backers are to blame for a purported chemical weapons attack near Damascus that the opposition says killed at least 100 people, the deadliest such attack in Syria's civil war.
Government forces, meanwhile, pummeled the targeted rebel strongholds where the alleged attack occurred with airstrikes and artillery for a second day, violence that was likely to complicate any swift investigation into the mysterious circumstances surrounding the deaths.
Deputy Prime Minister Qadri Jamil's comments were part of a government campaign to use the horror over the deaths to boost its narrative about the conflict -- that Syria is under assault by foreign Islamic radicals. It is an argument that has powerful resonance with the Syrian public as the presence of militants fighting alongside Syria's rebels increases.
Rebels blamed the attack on the Syrian military, saying toxic chemicals were used in artillery barrages on the area known as eastern Ghouta on Wednesday. Jamil did not directly acknowledge that toxic gas was used against the eastern suburbs but denied allegations by anti-government activists that President Bashar Assad's forces were behind the assault.
The murky nature of the purported attacks, and the difficulty of gaining access to the sites amid the carnage of Syria's war and government restrictions on foreign media, has made it impossible to verify the claims.
But they have fueled calls in the West for greater action against Assad's regime as amateur videos and photos showed images of the dead, including scores of lifeless children, wrapped in white cloths and lying shoulder to shoulder, while others struggled to breathe. Many pointed to the fact that their pale skin was unmarked by any wounds as evidence that it was a chemical attack.
The U.S., Britain and France along with a host of other countries demanded that a team of United Nations experts already in Syria be granted immediate access to the site. The timing of Wednesday's attack -- four days after the U.N. team's arrival -- has also raised questions about why the regime would use chemical agents now.
U.N. Secretary-General Ban Ki-moon added his voice to the calls on Thursday, urging the Syrian government to allow the U.N. team now in Damascus to swiftly investigate the alleged use of chemical weapons outside the capital.
President Barack Obama has called chemical weapons a "red line" for potential military action, and in June, the U.S. said it had conclusive evidence that Assad's regime had used chemical weapons against opposition forces. But it has so far shown no inclination to intervene.
State Department spokeswoman Jen Psaki said Thursday the administration was unable to conclusively determine the use of chemical weapons but added "we are focused every minute of every day since these events happened yesterday on doing everything possible within our power to nail down the facts."
Syria is said to have one of the world's largest stockpiles of chemical weapons, including mustard gas and the nerve agent sarin, but the government has never confirmed that.
Jamil said he was personally in favor of a fair, transparent international delegation to investigate the incident in Ghouta. But he said this requires a new agreement between the government and the U.N. and that the conditions for such a delegation would need to be studied.
"We don't want to be like Iraq, opening our territory up to all sorts of investigators, going through our homes and bedrooms. Syria is a sovereign nation and will preserve its sovereignty," he told the AP in an interview at the prime minister's offices in the Damascus district of Kfar Sousseh.
Denying that it carried out the attack, the regime has turned blame around to boost its narrative about the conflict -- that Syria is under assault by foreign Islamic radicals, an argument that has powerful resonance with the Syrian public as the presence of militants fighting alongside Syria's rebels increases.
Jamil said foreign militants carried out the attack with the backing of Israel and supporters in the West in a bid to thwart efforts to hold an international peace conference to end the Syrian bloodshed.
"We can only say that extremist forces carried it out, linked to foreign forces, since no Syrian can do this against another Syrian," he said. "At the head of these forces are those who have promoted vengeance and hatred and spoke of ousting the regime by force over the past two years."
The main state television news channel aired a documentary-style segment showing the pictures of the children's bodies lined up in their shrouds. "This is the brutality of the terrorists and those who have destructive plans for Syria," a voiceover intoned. "They trade in the lives of children, they use chemical weapons." The segment included an explanation of sarin gas, with diagrams of its effects on the body, though it didn't directly claim that sarin was used in Wednesday's attack.
Jamil estimated there were now 30,000 to 40,000 foreign fighters on Syrian soil from 70 countries.
"There are forces that have lost their minds and are using the most extreme weapons in their hands to prevent the international conference. They're in a state of insanity, they have lost their senses. It's a political attack as much as it's a chemical attack," he said.
Syrian opposition figures and activists have reported death tolls from Wednesday's attack ranging from 136 to 1,300. But even the most conservative tally would make it the deadliest alleged chemical attack in Syria's civil war.
U.N. deputy spokesman Eduardo del Buey said the U.N. chief has been in touch with world leaders since Wednesday and is sending U.N. disarmament chief Angela Kane to Damascus to press for an investigation.
A 20-member U.N. team led by Swedish chemical weapons expert Ake Sellstrom has been in Damascus since Sunday to investigate three sites where chemical weapons attacks allegedly occurred in the past: the village of Khan al-Assal just west of the embattled northern city of Aleppo and two other locations being kept secret for security reasons.
The opposition decried what is said were restrictions placed on the U.N. team by Assad's regime.
"The (U.N.) investigators came to Damascus to sit in the hotel and drink coffee, go out only with the regime's permission, visit what the regime wants and see what the regime wants. We don't need them in Damascus if that's how it's going to be," Louay al-Mikdad, a spokesman for the Western-backed opposition's military wing told Al-Arabiya TV.
The fighting raging in the Ghouta region -- the distant thuds could be heard in the capital -- as Syrian government forces pressed their offensive was likely to complicate even further the U.N. experts' visit to the area where they would need to cross between government and rebel-held territory.
Warplanes conducted several air raids on the eastern and western suburbs of Damascus, including three that took place within five minutes, and regime forces shelled eastern Ghouta from the picturesque Qasioun mountain overlooking Damascus, activists said.
Mohammed Abdullah, an activist in the suburb of Saqba, told the AP via Skype on Thursday that most of the dead were buried hours after the attack in collective graves in different areas in eastern Ghouta. The burials took place quickly for fear the bodies might decompose as in the heat, he said.
France, meanwhile, raised the possibility of the use of force in Syria if it is proven that Assad's regime used chemical weapons, while Turkey said several red lines have been crossed.
"We need a reaction by the international community .... a reaction of force," said French Foreign Minister Laurent Fabius. He excluded soldiers on the ground as an option, though, and declined to be "more precise" on the type of force that could be used.
The state news agency also reported that a suicide bomber attacked a sports facility in the northern city of Aleppo where a family was holding a party for a schoolgirl who passed her high school tests. Seven people were killed, including the girl and Hassan Mhanna, a journalist working for the state-run Al-Ikhbariya channel.
The unrest in Syria began in March 2011 and later exploded into a civil war. More than 100,000 people have been killed, according to U.N. figures.