America the Free, Home of the Assholes.

The United States is operating "floating prisons" to house those arrested in its war on terror, according to human rights lawyers, who claim there has been an attempt to conceal the numbers and whereabouts of detainees.

The analysis, due to be published this year by the human rights organisation Reprieve, also claims there have been more than 200 new cases of rendition since 2006, when President George Bush declared that the practice had stopped.

According to research carried out by Reprieve, the US may have used as many as 17 ships as "floating prisons" since 2001. Detainees are interrogated aboard the vessels and then rendered to other, often undisclosed, locations, it is claimed.

The Reprieve study includes the account of a prisoner released from Guantánamo Bay, who described a fellow inmate's story of detention on an amphibious assault ship. "One of my fellow prisoners in Guantánamo was at sea on an American ship with about 50 others before coming to Guantánamo ... he was in the cage next to me. He told me that there were about 50 other people on the ship. They were all closed off in the bottom of the ship. The prisoner commented to me that it was like something you see on TV. The people held on the ship were beaten even more severely than in Guantánamo."

"By its own admission, the US government is currently detaining at least 26,000 people without trial in secret prisons, and information suggests up to 80,000 have been 'through the system' since 2001. The US government must show a commitment to rights and basic humanity by immediately revealing who these people are, where they are, and what has been done to them."

A US navy spokesman, Commander Jeffrey Gordon, told the Guardian: "There are no detention facilities on US navy ships." However, he added that it was a matter of public record that some individuals had been put on ships "for a few days" during what he called the initial days of detention. He declined to comment on reports that US naval vessels stationed in or near Diego Garcia had been used as "prison ships".

CIA "black sites" are also believed to have operated in Thailand, Afghanistan, Poland and Romania.

In addition, numerous prisoners have been "extraordinarily rendered" to US allies and are alleged to have been tortured in secret prisons in countries such as Syria, Jordan, Morocco and Egypt.