LONDON (AFP) - British Prime Minister David Cameron led parliament in a special session of tributes to Margaret Thatcher on Wednesday, describing the divisive former leader as an "extraordinary" woman who had revived the country's fortunes.

The Iron Lady's harshest critics stayed away in a sign of her bitterly disputed legacy, but the Houses of Commons and Lords were mostly packed full of lawmakers recalled from their holidays after Thatcher died on Monday aged 87.

"Let this be her epitaph, that she made this country great again," said Mr Cameron, a fellow Conservative.

Hailing her as "an extraordinary woman", he said Mrs Thatcher was also renowned internationally for helping defeat communism during the 1980s and ending the Cold War.

"Today, in different corners of the world, there are millions of people who know that they owe their freedom, in part, to Margaret Thatcher," Mr Cameron said.

Supporters say Mrs Thatcher's free-market reforms made Britain stronger and hail her leadership during the 1982 Falklands War with Argentina. However, critics complain her economic policies and battles with the trade unions destroyed millions of lives.

Opposition Labour leader Ed Miliband acknowledged her impact on Britain, telling the House of Commons: "Whatever your view of her, Margaret Thatcher was a unique and towering figure." Mrs Thatcher's son Mark said their family had been "overwhelmed" by messages of support they had received from around the globe, following her death at London's Ritz hotel after a stroke.

He said Mrs Thatcher would also have been "greatly honoured" by Queen Elizabeth II's decision to attend her funeral next Wednesday, a rare honour from the monarch only previously accorded to wartime prime minister Winston Churchill, who died in 1965.

The ceremony will be held at St Paul's Cathedral in London, where British armed forces personnel from units associated with the Falklands conflict will bear her coffin. A total of 700 military personnel will be involved.

Mr Cameron said her casket would be draped with the British flag as it was transported on a gun carriage to the cathedral, saying: "This will be a fitting salute to a great prime minister." In warm-hearted and often emotional debates in both chambers of parliament, Mrs Thatcher's former colleagues exchanged anecdotes about her strength of conviction but also her personal kindness.

Senior Tories Norman Tebbit and John Wakeham spoke movingly of her sympathy following to the IRA bombing at the Conservative party conference in 1984, from which Thatcher narrowly escaped but which killed Wakeham's wife and paralysed Tebbit's.

Mr Malcolm Rifkind, who served in Mrs Thatcher's government for the full 11 years, recounted how life with her "was never dull", while former Liberal Democrat leader Paddy Ashdown described her as "infuriating" but "without a doubt the commanding politician and the greatest prime minister of our age".

However, several of her biggest critics boycotted the debates.

"Her impact and influence is indisputable, but her legacy is too bitter to warrant this claim to national mourning," said one Labour lawmaker who stayed away, John Healey.

Firebrand left-wing lawmaker George Galloway also said he would boycott what he derided as a "state-organised eulogy".

Security for next week's funeral is likely to be extremely tight with fears of disruption by Irish republican dissidents and far-left groups. Police are also reportedly bracing for a possible "lone wolf" attack.

Concerns about potential violence rose after trouble erupted at several street parties celebrating her death on Monday night in London, Liverpool, Bristol and Glasgow.

Many world figures are expected to attend Mrs Thatcher's funeral, although a spokesman for former Soviet leader Mikhail Gorbachev said he would not be among them because his health was too frail.

Former Labour prime minister Tony Blair and his wife were among the first confirmed guests to the ceremony, which will be followed by a private cremation.

Mrs Thatcher's ashes will be laid next to those of her husband Denis, who died in 2003, at the Royal Chelsea Hospital.

Mr Mark Thatcher was out of the country when his mother died, as was his sister, but he returned overnight to the family's plush central London townhouse, where well-wishers had left flowers and tributes.

"We have quite simply been overwhelmed by messages of support, condolence, of every type from far and wide and I know that my mother would be pleased they have come from people of all walks of life," the 59-year-old told reporters.

Several Conservative lawmakers have called for Mrs Thatcher to receive a full state funeral but her spokesman Lord Tim Bell said Mrs Thatcher had specifically asked not to have one.

The government dismissed criticism over the cost of the ceremony, which is less ostentatious than the state funeral given to Mr Churchill but is the same honour afforded to the Queen Mother and Princess Diana.

"I think we can afford to contribute to a funeral," Foreign Secretary William Hague told the BBC.

Mrs Thatcher and her policies, dubbed "Thatcherism", remain as divisive now as they were during her premiership from 1979 to 1990.

A YouGov poll of almost 2,000 people published on Wednesday found that 28 per cent of people regarded her as Britain's greatest prime minister - even more than Mr Churchill.

Overall, 52 per cent thought she was a good or great premier while 30 per cent thought she was poor or terrible.