[JURIST] According to British Foreign & Commonwealth Office documents obtained and published Saturday by the Guardian newspaper, Martin Mubanga, one of four muslim Britons still held at Guantanamo Bay, made new allegations of torture and humiliation endured by him and other detainees during a recent "welfare visit" from an FCO official. Mubanga, 31, claimed that he was recently shackled so long that he wet himself and then was forced to clean his own urine. He also alleged that he was threatened, abused, and subjected to extreme temperatures. Further allegations of mistreatment appeared in a letter [PDF] from Moazzam Begg, one of five Britons released from Guantánamo last March. In response, a Foreign Office spokeswoman said that they had raised the claims with US authorities, who investigated them and found them to be "without merit." The Guardian has more