Five Americans facing charges for allegedly plotting attacks against Pakistan and its allies alleged they were tortured in custody, as a Pakistani court on Monday extended their detention.

The five young men were arrested in December on suspicion of trying to contact Al-Qaeda-linked groups, with police officials accusing them of trying to travel to Afghanistan to fight with the Taliban against US and NATO troops.

"We are being tortured, we are being tortured," several of the men shouted in English from a prison van as it left a court in Sargodha town in eastern Pakistan after their hearing, which took place under tight security.

Jehangir Sarwar, a senior lawyer present in the courtroom, quoted one of the five men as complaining of "police excesses".

Sarwar, who was in the court as an observer and was not representing anyone, did not say which of the five men made the remark, while police officials denied that mistreatment was raised during the brief hearing.

"None of the five men said anything of the sort in the court. As far as I know, one of these men had a stomach problem," said Aamir Abbas, a local police official who worked on the case.

He said that the court extended judicial remand of the five men until February 2 when they will be produced again before the court.