TRENTON, New Jersey -- Less than a month after buying Wyeth, drug giant Pfizer Inc. has mapped out a new structure for its research and development operations.

The plan, announced Monday, will bring the closure of six of their 20 research facilities, reorganize and consolidate others, and cut the jobs of roughly 15 percent of scientists and laboratory technicians.

New York-based Pfizer solidified its position as the world's biggest drugmaker with its $68 billion purchase of drug and vaccine maker Wyeth on Oct. 15.

The two executives heading the combined research operation told The Associated Press exclusively that integrating and reorganizing the two companies' laboratories will boost research productivity and efficiency and save money as well.

In addition, Pfizer will eliminate about 35 percent of the 16 million square feet (1.5 million sq. meters) of research space it now has around the world.

It will now have five key research centers, each focused on a couple of specific disease areas, plus nine other laboratories with specialized research capabilities. Research operations in Princeton, New Jersey; two sites each in New York and North Carolina, and one in the United Kingdom will be closed.

"We have really built the very best from the two companies," Martin Mackay, president of research and development for pills and other traditional medicines, said in an interview.

The five primary research centers will be two Wyeth facilities, in Cambridge, Massachusetts, and Pearl River, New York, and three Pfizer facilities, in La Jolla, California; Groton, Connecticut, and Sandwich, United Kingdom.

Major sites being consolidated including a sprawling Wyeth facility in Collegeville, a suburb of Philadelphia, and a large facility in the St. Louis suburb of Chesterfield, Missouri, that is being sold back to its original owner, Monsanto Co., for $435 million. Pfizer will retain a small research operation there, a spokeswoman said.

Before the companies combined, Pfizer had about 9,000 researchers and technicians, and Wyeth roughly 4,500. Besides those losing their jobs, some will be asked to move to other sites.

Savings from the job cuts and the plant closures will be poured into research on key diseases Pfizer is targeting, including Alzheimer's and other neurological diseases, cancer, pain and inflammation, diabetes and infectious diseases, plus new vaccines.

"We essentially will have a portfolio up and running on the diseases that we care about this year," said Mackay.

That's an unusually fast transition for an already-huge company that just completed one of the industry's biggest deals ever.

By comparison, when Pfizer acquired Warner-Lambert Co. in 2001, it spent the next two years making a series of decisions about what to do with different parts of the research organization. It still hadn't finished the integration of the two companies when it bought another drugmaker, Pharmacia Corp., in 2003.

Moving quickly to eliminate uncertainty for employees is essential for maintaining research productivity and innovation, as well as "employee dedication," said Mikael Dolsten, president of research and development for vaccines and biotech drugs.

Those areas were both strengths of Wyeth's, key reasons Pfizer bought the company, which was based in Madison, New Jersey.

Affected employees were being notified today.

Monday's announcement "will allow many of our external partners to know which sites, which units they'll be working with," Dolsten said.

In midday trading, Pfizer shares rose 40 cents, or 2.4 percent, at $17.36.