Pakistan police are trying to determine whether five arrested Americans planned to attack a nuclear power complex.

The young Muslim men from the Washington DC area, were picked up in Pakistan earlier this month in a case that has spurred fears that Westerners are travelling there to join militant groups.

Pakistani police and government officials have made a series of escalating and, at times, seemingly contradictory allegations about the men's intentions, while US officials have been far more cautious, though they, too, are looking at charging the men.

A Pakistani government official said that the men had established contact with Taliban commanders and planned to attack sites in Pakistan.

Earlier, local police accused the men of intending to fight in Afghanistan after meeting militant leaders.

The men had a map of Chashma Barrage, a complex that along with nuclear power facilities houses a water reservoir and other structures, said Javed Islam, a senior police official in the Sargodha area of Punjab province.

He stressed the men were not carrying a specific map of any nuclear power plant, but rather the whole of Chashma Barrage.

The detained men had also exchanged emails about the area, Islam said.

"We are also working to retrieve some of the deleted material in their computers," he said.

Pakistan has a nuclear weapons arsenal, but it also has nuclear power plants for civilian purposes.

Any nuclear activity in Pakistan tends to come under scrutiny because of the nation's past history of leaking sensitive nuclear secrets due to the actions of the main architect of its atomic weapons programme, Abdul Qadeer Khan.

But as militancy has spread in Pakistan, officials have repeatedly insisted the nuclear weapons programme is safe.

Pakistani police plan to recommend that courts charge the five men with collecting and attempting to collect material to carry out terrorist activities in the country, police official Nazir Ahmad said.

The punishments for those charges range from seven years to life in prison.

Officials in both countries have said they expected the men would eventually be deported to the US, but charging the men in Pakistan could delay that process - Pakistan's legal system can be slow and opaque.

In an interview with The Associated Press yesterday, Punjab province law minister Rana Sanaullah said the men had established contact with Taliban commanders.

He said they had planned to meet Pakistani Taliban chief Hakimullah Mehsud and his deputy Qari Hussain in Pakistan's tribal regions before going on to attack sites inside Pakistan.

The nuclear power plant "might have been" one of the targets, Mr Sanaullah said.

The FBI, whose agents have been granted some access to the men, is looking into what potential charges they could face in the US. Possibilities include conspiracy to provide material support to a terrorist group.

The US embassy would not comment on the potential charges or say what efforts Washington was making to bring the men back.

The five were arrested in Sargodha earlier this month, but are being held in Lahore.