WASHINGTON: Seventy-four, or one out of every seven, terrorism suspects formerly held at the US detention site at Guantanamo Bay are confirmed or suspected of having returned to terrorism, the Pentagon said on Tuesday.

Of more than 530 detainees transferred from the US base in Cuba, 27 are confirmed and 47 suspected of "reengaging in terrorist activity," according to a written Pentagon summary.

The total of 74 has more than doubled since May 2007, when the Pentagon said about 30 had gone back to terrorist activity, and increased slightly since January, when the figure stood at 61.