A Red Cross team has begun its inspection of the conditions in which about 80 al-Qa'ida and Taliban fighters are being held at the Guantanamo Bay prison camp, amid growing diplomatic tensions between the US and Britain.

The four-strong team from The International Committee of the Red Cross (ICRC) will spend up to a week at the base on Cuba, interviewing and registering the prisoners before compiling a confidential report which it will present to the US authorities.

A further 30 prisoners arrived last night at Camp X-Ray, the specially constructed prison at Guantanamo, bringing the total number to 110.

Meanwhile, fresh signs of diplomatic tension between London and Washington over the fate of the captives emerged last night as the Government said it wanted independent confirmation they were being treated properly.

Robin Cook, the Leader of the House, took a swipe at assurances from the US Defence Secretary, Donald Rumsfeld, that the prisoners' treatment was "reasonably consistent" with the Geneva Convention. He said: "I am not sure you would take Mr Rumsfeld's views as independent corroboration. He is a man of robust views."

Ann Clywd, chair of the Commons human rights group, said: "We were in coalition with the Americans... We will be criticised, quite rightly, for not showing concern for prisoners we may well have captured. Britain should not be allowed to wash its hands of them."

The growing controversy over Guantanamo Bay was touched on during a 30-minute telephone call yesterday between Tony Blair and President George Bush. The Prime Minister said afterwards: "We both agreed that people should be treated humanely."