NEW YORK, March 8: The Pakistan government is pursuing large numbers of Taliban and Al Qaeda fighters who have crossed into the country from Afghanistan in recent months and are now believed to be hiding in tribal villages or large cities, said the New York Times on Friday.

At the same time, though Pakistani troops encountered more fighters trying to slip into Pakistan this week, said the paper quoting Pakistani officials who asserted that the border was mostly secure and that they did not believe that the forces now battling American troops in eastern Afghanistan had re-entered Afghanistan from Pakistan.

They said they believed that those forces were among the Taliban and Al Qaeda fighters who had adopted a low profile after the fall of Kabul but never left Afghanistan, and had kept their military supplies there.

“They didn’t need to be supplied from the Pakistani side of the border, which is effectively sealed,” a senior Pakistani military officer told the paper. The officials told the Times that they estimated that as many as 1,800 Al Qaeda members and more than 3,500 Taliban fighters might have slipped into Pakistan since November. Only about 600 have been detained by Pakistani authorities, one senior Pakistani intelligence officer said.

Of those detained, about 280 have been handed over to the United States, but none are major leaders of either Al Qaeda or the Taliban.

Pakistani officials said the flow of Taliban and Al Qaeda fighters into the country was at its peak in December and early January and had since declined considerably.