Tony Blair defends his government against the latest allegations

Mr Blair told BBC One's Breakfast with Frost that stories in Sunday's papers were "a whole lot of nonsense" and gave his full backing to Foreign Secretary Robin Cook.

Key policy announcements will be made by the government this week, but they are in danger of being overshadowed by the sex and drinking allegations against Mr Cook, detailed in a book by his former wife.

Mr Blair denied that the new claims against the foreign secretary damaged the dignity of his office and described him as "the most respected foreign minister in the rest of Europe that we've had for years and years and years".

The BBC's John Pienaar: "It's very embarrassing for Cook and Blair"

"I have every confidence in the job he does," Mr Blair said, adding that "if you go through any big corporation" employees had problems in their private lives that did not affect the way they carried out their jobs.

Rounding on the media, he said the government should be judged on its ability to deliver on election pledges, not "scandal, gossip and trivia".

"If we haven't delivered by the next election, judge us on that. Judge us on the things that really matter," he said.

Gordon Brown: Allegations over girlfriend's firm

"Do we really want the whole lot of politics diminished to the level of a gossip column?"

In a wide-ranging interview that touched on the health service, welfare reform, Northern Ireland, Lords reform and the euro, Mr Blair sought to deflect interest away from the government's present difficulties and set out its agenda for 1999.

Mr Blair said he was "philosophical" about what has been described as his worst three weeks in office - during which two ministers were forced to quit over an undeclared loan and allegations were made about bitter "turf wars" between Cabinet ministers.

Tim Yeo: "Snouts in the trough"

In an earlier interview on GMTV's Sunday programme, Conservative Leader William Hague accused Mr Blair of a "failure of leadership".

"The endemic problem of this government is that it doesn't stand for any fundamental policies or beliefs. It just stood for being in office with all the feuding and rivalries," he said.

"That is a problem that goes right to the top."

In addition to addressing claims about Mr Cook, the prime minister said he was "getting pretty tired" of having to stifle allegations of a rift between himself and Chancellor Gordon Brown.

Mr Brown has also been accused of "driving a coach and horses" through ministerial code after it emerged that a PR firm run by his girlfriend Sarah Macaulay had been hired by former Paymaster General Geoffrey Robinson.

It was claimed Ms Macaulay's firm, Hobsbawm Macaulay Communications, was paid more than £100,000 for public relations work for Mr Robinson's magazine, The New Statesman.

Jack Cunningham: Accused of using private jets at taxpayers' expense

Shadow Chief Secretary David Heathcoat Amory said that deal breached the code of conduct that says ministers and their spouses and partners must avoid the appearance of any conflict of interest.

And the Tories sought to exploit potential rifts between ministers by attacking Cabinet "enforcer" Jack Cunningham for wasting public money by chartering jets to attend meetings - revelations reportedly made by his successor as agriculture minister, Nick Brown.

Shadow Agriculture Minister Tim Yeo rounded on Dr Cunningham - now minister for the Cabinet Office - for having "been caught with his snout in the trough".

"It is significant that Nick Brown was so keen for everyone to know of Mr Cunningham's extravagance," he said.