US Secretary of State Hillary Clinton has questioned Pakistan's failure to capture senior al-Qaeda leaders.
In an interview with journalists in Lahore, Mrs Clinton said she found it "hard to believe" nobody in the government knew where they were.
Mrs Clinton was in Pakistan for two days to strengthen ties with the government, shore up the fight against militants and tackle rising anti-US feelings among the Pakistani people, the BBC reports.
In the interview on Thursday, she was asked why Pakistan was seen as the centre of terrorism and why other nations could not do more in the fight against it.
Mrs Clinton said: "The world has an interest in seeing the capture and killing of the people who are the masterminds of this terrorist syndicate. As far as we know, they are in Pakistan."
She said: "Al-Qaeda has had safe haven in Pakistan since 2002... I find it hard to believe that nobody in your government knows where they are and couldn't get them if they really wanted to.
"Maybe that's the case; maybe they're not gettable. I don't know."
Ambassador Anne Patterson said Mrs Clinton's remarks were similar to what Pakistani officials had been told privately by the the Obama administration.