Tony Blair insisted last night he was fit and well after being given the all-clear by doctors who had feared he was suffering from appendicitis.

Mr Blair was questioned by reporters as he left No 10 for engagements in Wales and, asked how he was, replied: "I'm fine."

Earlier, No 10 said the two doctors who examined Mr Blair on Wednesday night after he complained of stomach pains had returned for a second visit yesterday.

They confirmed no treatment was required and they did not plan to see him again.

Journalist Sir Trevor Macdonald, who saw Mr Blair yesterday for a charity event, said the Prime Minister told him it was feared at first he had appendicitis.

The Premier's official spokesman refused to confirm what was wrong with Mr Blair, who was involved in another health scare when he was taken to hospital last month with an irregular heartbeat.

The spokesman said: "My understanding is it could have been one of a number of things, none of which is a cause for concern."

He said the Prime Minister was taken unwell inside No 10 between 6pm and 7pm on Wednesday.

"He wasn't feeling great, and so he saw doctors, and the problem appeared to pass pretty quickly. He was feeling fine later."