The Pakistani authorities say that five men who had been studying in the United States have been arrested in Pakistan on suspicion of being connected to extremist groups.
The US Federal Bureau of Investigation (FBI) says it's checking whether the five are the same men who were reported missing from their American homes late last month. The US State Department says it's also seeking information on the men.
The five were arrested in a raid on a house in Sarghoda in eastern Punjab province, Pakistan's US embassy has told the BBC. Three are reported to be of Pakistani descent, while the others are said to have Egyptian and Yemeni backgrounds.
The embassy says that they were arrested in a house belonging to an uncle of one of them but that no charges have yet been laid.
Secretary of State Hillary Clinton has declined to comment on the arrests, according to the Reuters news agency, but has said that the US has to "work more closely with both Afghanistan and Pakistan to try to root out the infrastructure of terrorism that continues to recruit and train people".
Video left behind 'like a farewell'
The five men, all students, were reported missing from their homes in northern Virginia by their families, who reportedly passed on a video to members of the US Council on American-Islamic Relations (CAIR).
Nihad Awad, the leader of CAIR, says the video appeared to be "like a farewell".
"One person appeared in that video and they made references to the ongoing conflict in the world, and that young Muslims have to do something," Mr Awad has told the Associated Press news agency.
He says the video made him "uncomfortable" and he advised the men's families to contact the FBI.