In a series of broadcast interviews and a high-profile press conference at 10 Downing Street, Mr Brown repeatedly stressed his determination to take decisions in Britain's long-term interests, even if they prove unpopular in the short term.

He dismissed speculation over possible challenges to his position as "rumour and gossip" which would not distract him from "getting on with the job" of being Prime Minister.

Labour's drubbing at this month's local elections and a series of poor poll ratings ahead of next week's Crewe and Nantwich by-election have led to open discussion of whether Mr Brown will stay on to lead the party into the coming General Election.

But he told his press conference: "I'm getting on with the job. I'm getting on with the job of building for the long-term and taking sometimes unpopular decisions which are necessary so we can show the country that we are preparing this country - which has a huge and magnificent future ahead of us if we take the right long-term decisions.

"I am determined not to be diverted from taking these long-term decisions."

Mr Brown acknowledged there were "many people" in his Cabinet who were capable of being Prime Minister.

But he added: "Of course they are capable of doing the job, but I'm doing the job. I was elected unopposed and I think that people understand that we are getting on with the job and I am not going to be distracted by this gossip."

Mr Brown said that Britain's economic challenges stemmed in large part from the credit crunch resulting from events in America and from higher oil and food prices caused by higher demand from emerging Asian giants China and India.

Countries all over the world were facing the same problems, but Britain was better placed than most because of its record over the past decade of low debt and low unemployment, he said.