Sir Cliff said Mr Blair looked like he was going through a "horrible" time

Mr Blair and his family spent three weeks in the Caribbean villa in August at the height of the Iraq crisis.

"I saw him during the war and I thought this man has made this decision and he's living it in front of us," the 63-year-old singer told Sky News.

"He seemed to change - he became gaunt, tired, ancient-looking suddenly."

Mr Blair at a press conference before going on holiday in August

The summer holiday came just before Mr Blair gave evidence at the Hutton inquiry into the death of Iraq weapons expert Dr David Kelly.

Sir Cliff said he telephoned the prime minister's wife, Cherie Blair, and said it looked "horrible" and "terribly difficult".

"All I know is that a human friend of mine looked as though he needed a rest.

"I said 'please, if you can find the time to go, I won't be there, but feel free to use the place.'

"I may not offer that again, but I was happy that I did because he did benefit from it physically."

On Tuesday, Mr Blair admitted the role of British prime minister was a tough one, but insisted he was "feeling great".