In her first major statement on the crisis in Kosovo, the former Tory premier said Nato was fighting a war "eight years too late".

Speaking at a gathering to mark the 20th anniversary of her entry into Downing Street, Lady Thatcher said: "We are not dealing with some minor thug, but with a truly monstrous evil."

She said Yugoslav President Slobodan Milosevic "cannot with safety be merely checked or contained" but "must be totally defeated".

'Long haul'

She added: "We must be prepared to cope with all the changing demands of war - including, if that is what is required, the deployment of ground troops. And we must expect a long haul until the job is done."

The BBC's Carole Walker: "These were her first public comments on Kosovo"

Downing Street has welcomed Lady Thatcher's remarks. A spokesman said: "The prime minister has always been very grateful of the support Lady Thatcher has given to the government over Kosovo.

"Her speech underlines just why Nato are taking this action against the Milosevic regime."

Mr Blair says Serb forces have been hit hard

Earlier, UK Prime Minister Tony Blair insisted that Nato will see its Kosovo campaign through until it achieves its aims.

Speaking during a visit to Belgium for a series of meetings with military and political leaders, he emphasised the moral case for military action.

David Shukman reports on Tony Blair's effort to boost the Nato war of words

Mr Blair also gave an upbeat progress report about the success rate of Nato air raids, saying they had severely damaged the "killing machine" of President Milosevic.

"I assure you of our determination to see this through to the end," he told a news conference at Nato headquarters in Mons.

Only Nato can help the refugees get home Mr Blair says

"My generation never thought to see those scenes in Europe again, and our task is very simple and our will in seeing it through must be absolute and total," he said.

"I think there is a proper sense of moral outrage about what Milosevic has done that we should not shy away from and should feel proud to be feeling."

Mr Blair also insisted that the success of Nato's action was "the only chance" that the refugees had of returning home.

Air raid destruction

The prime minister said at least 13 different military targets had been hit by Nato raids on Monday night.

The vehicles destroyed included five tanks, four armoured personnel carriers and about 20 other military vehicles, he said.

A troop assembly area, a surface-to-surface missile system, ammunition depots, army headquarters, airfields, oil depots and refineries and "other parts of the Serb military machine" were also attacked.

Mr Blair detailed the losses to the Serbian air force and fuel depots and supply routes.

Earlier, Mr Blair delivered a personal message of support to Nato's commanders via a video link.

In a message beamed to officers across Europe, he said: "You are fighting a just war in a just cause."