His comments came as Nato again carried out heavy air attacks on Yugoslavia despite the accidental bombing of a refugee convoy by one of its planes on Wednesday.

Mr Rifkind, who lost his seat as a Conservative MP at the last general election, told BBC One's Breakfast News: "I very much fear bombing alone is unlikely to succeed.

"There has to be a diplomatic initiative to get an honourable settlement in Kosovo.

"But it must be a diplomatic effort which is backed by the credible threat of and use of ground forces.

More British troops are leaving for the Balkans

"It must also be a diplomatic initiative which includes the Russians as well as Nato because the Russians have far more influence in Belgrade than anyone else."

He added that Nato was acting "honourably" in its bombing campaign.

"I think bombing is morally justified given the ghastly ethnic cleansing that is going on in Kosovo."

Meanwhile, three British ships carrying supplies including 14 Challenger tanks and armoured vehicles are leaving for the region.

Two vessels are expected to sail on Friday and a third on Saturday.

Campaign talks

The supplies are part of a battle group which will include 2,000 troops, taking the total number of British troops in the region to more than 6,300.

UK Defence Secretary George Robertson was in the United States on Friday for talks with his American counterpart about the Kosovo crisis.

Mr Robertson and US Defence Secretary William Cohen are scheduled to spend two days discussing the Nato military campaign in the Balkans.

The meeting comes just a week before a Nato Washington Summit.

French soldiers patrol the Kosovo border

Nato says it is carrying out a full investigation into the accidental bombing of a refugee convoy in Kosovo.

There is still uncertainty over the exact circumstances surrounding the attack.

The alliance has said one of its planes bombed one vehicle in a convoy. The Serbs said on Wednesday that more than 60 refugees had been killed in at least two attacks.

Refugee deaths 'regrettable'

But Nato leaders cast doubt on whether footage broadcast by Serb TV showed their attack or another incident, or incidents, elsewhere.

Nato said its aircraft had later attacked a second convoy, but had hit only military targets.

Some refugees in a third convoy reported that they had been attacked by Serb aircraft.

President Clinton called the deaths of scores of people "regrettable, but inevitable".

UK Armed Forces Minister Doug Henderson said the Pentagon may have denied the reports at first because they were acting on the best information available.