(CBS) British attorneys have begun a new effort to get legal representation for the suspected al Qaeda and Taliban prisoners being held in Cuba, reports CBS News Correspondent Sam Litzinger.

Three hundred prisoners captured in Afghanistan are being held at Camp X-Ray, a U.S. Navy detention center at Guantanamo Bay in Cuba. At least five Britons are among them.

"The British government must not stand by silently while the basic rights of British detainees are being trampled on by the U.S.," said Mark Muller, deputy chair of the Bar Human Rights Committee.

Zumrati Juma says she hasn't seen her 22-year-old son, Feroz Abbasi, in months, but he's a good person nonetheless.

"I do not believe that he would have got involved in terrorism," she told reporters.

Louise Christian, representing one of the British Muslim detainees and his mother, told a news briefing the government had until the end of Tuesday to react to demands for greater access to British prisoners and for basic human rights to be guaranteed.

"A state can be responsible if it aids and abets the unlawful act of another state knowingly," she said, adding that British foreign intelligence officers had interviewed Guantanamo Bay detainees and passed the information to the United States, making it a party to what happened there.

She added that U.S. Defense Secretary Donald Rumsfeld apparently has "no respect for the rule of law," and said the U.S. is being unfair to the British prisoners "because the only U.S. person arrested in Afghanistan, John Lindh Walker, has been taken back to trial in the U.S.

She termed the conditions in which the detainees in Guantanamo are being held "an absolute outrage."

The detainees' treatment has become a source of tension between America and its European allies. U.S. authorities call the detainees "illegal combatants" rather than prisoners of war, and President Bush initially refused to apply the Geneva Conventions, which outline the rights accorded prisoners of war.

The White House now says that the Taliban fighters, but not those linked to al Qaeda, will be protected by the conventions.

The Bar Council, which represents barristers, and the Law Society, the self-governing body for solicitors, want the Britons to be allowed access to lawyers and returned to Britain to face trial.

Last Thursday a U.S. federal judge dismissed a petition by civil rights advocates who want the Guantanamo detainees to be brought before a U.S. court.