Madeleine Albright and Robin Cook speaking on the BBC's Today programme

The pair stressed their continuing support for Nato's air campaign, despite reports that the Swiss Ambassador's residence was damaged in the latest strikes on Belgrade.

Mr Cook and Mrs Albright embarked on a whistle-stop tour of TV appearances in the US.

The trip was planned following media reports claiming that the US President Bill Clinton was not as keen as the UK Prime Minister Tony Blair to send ground troops into Kosovo.

But Mr Cook said: "There are no closer allies within the alliance than Britain and the United States.

'Determined to prevail'

He and Mrs Albright also stressed that they enjoyed a close working relationship which they said was symbolic of Nato's resolve to end ethnic cleansing in Kosovo.

The BBC's Stephen Sackur: "The debate over ground forces has exposed differences between London and Washington"

"We are a sign of the way that the alliance is working, and the alliance is determined to prevail," Mrs Albright said.

The show of unity appeared to be intended to counter reports of a rift between the UK and US over Nato's strategy.

According to The New York Times, Mr Clinton telephoned Mr Blair on Tuesday to complain about the stories which spoke of divisions over the use of ground troops.

The Times newspaper said Mr Clinton urged the prime minister to "get control".

'No option off the table'

Mr Cook and Mrs Albright stressed that their governments remained committed to continuing Nato's bombing campaign, which they said had inflicted major damage on the Serb military structure.

Washington Correspondent Paul Reynolds: "Americans do not want to discuss ground troops in detail"

But they refused to rule out the possibility that ground troops might enter Kosovo to take on hostile Serb forces.

Mrs Albright said the member governments were currently waiting for the alliance's military commanders to update their assessments on the feasibility for both "a permissive and non-permissive" deployment of ground troops.

"We have not taken any option of the table," Mrs Albright said.

She also dismissed reports of a wider split within Nato.

"This alliance is unified in a way which many people predicted could not be possible. We really have 19 democracies working together for the same goals and the same purpose," she said.