The Latest: US military probing reports of strike on IS jail

BEIRUT (AP) - The Latest on the White House saying it has "potential" evidence that Syria's government is preparing another chemical weapons attack (all times local):

3:40 p.m.

The U.S. military says it will assess allegations that a coalition airstrike may have killed over 40 prisoners held in an Islamic State-run jail in eastern Syria.

Central Command confirmed to the AP on Tuesday that it struck IS facilities in the town of al-Mayadeen in the province of Deir El-Zour the day before.

Syrian activists reported an IS jail was struck in the area on Monday, and said at least 42 prisoners were killed, along with several IS fighters.

CENTCOM said it would publish the results of its assessment in its monthly civilian casualty report.

It said the Mayadeen mission was "meticulously planned and executed to reduce the risk... to non-combatants."

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1:50 p.m.

The Kremlin is dismissing the White House's warning that the Syrian government is preparing a new chemical attack and that President Bashar Assad and his military "will pay a heavy price" if it goes ahead.

Russian President Vladimir Putin's spokesman Dmitry Peskov says that "such threats to Syria's legitimate leaders are unacceptable."

Russia is Assad's key backer and sided with him when he denied responsibility for a chemical weapons attack that killed dozens of people in Idlib province on April 4.

Days later, President Donald Trump ordered a retaliatory cruise missile strike on a Syrian government-controlled air base.

Peskov criticized the Trump administration for using the phrase "another chemical weapons attack," arguing that an independent investigation into the April attack was never conducted despite Russia's calls for one.

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1:30 p.m.

Syrian activists say an airstrike targeting an Islamic State-run jail in eastern Syria has killed at least 42 prisoners.

The Britain-based Syrian Observatory for Human Rights says at least 15 IS jailers and fighters were also killed in the airstrike that happened on Monday in the Deir El-Zour province.

The activist-run Deir Ezzor 24 media outlet says at least 60 civilians were killed. It says the building belonged to an al-Qaida-linked commander before it was seized by the IS group in 2014.

The two groups said the U.S.-led coalition was behind the strike. It was not clear how they identified the aircraft responsible. The coalition could not immediately be reached for comment.

In addition to the coalition, Russia and Syria often carry out airstrikes against IS in eastern Syria.

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12:45 p.m.

A Syrian minister has dismissed a White House statement alleging that President Bashar Assad's government is preparing a new chemical weapons attack, saying Damascus has not and will not use such arms.

Ali Haidar, the minister for national reconciliation, told The Associated Press on Tuesday that the White House statement foreshadowed a "diplomatic battle" that would be waged against Syria in the halls of the U.N.

The U.S. holds Assad's government responsible for two sarin gas attacks that together killed hundreds of civilians in 2013 and earlier this year.

The White House statement on Monday night was made without forewarning and caught State Department officials by surprise.

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3 a.m.

The White House has issued a stern warning to Syrian President Bashar Assad, claiming "potential" evidence that Syria was preparing for another chemical weapons attack.

In an ominous statement issued late Monday with no supporting evidence or further explanation, Press Secretary Sean Spicer said the U.S. had "identified potential preparations for another chemical weapons attack by the Assad regime that would likely result in the mass murder of civilians, including innocent children."

He said the activities were similar to preparations taken before an April 2017 attack that killed dozens of men, women and children, and warned that if "Mr. Assad conducts another mass murder attack using chemical weapons, he and his military will pay a heavy price."

The White House offered no details on what prompted the warning.