POLICE are monitoring groups who plan to hold parties in Edinburgh and Glasgow tonight to celebrate the death of Margaret Thatcher amid fears they may escalate into violence.

More than 350 people had pledged to attend a demonstration in Glasgow's George Square while a separate event was being organised on social media for the Mound in Edinburgh.

One attending the "celebration" in Glasgow wrote online: "We can't let this event pass without a celebration. Bring sound systems, effigies to hang from lamp posts, food, drink."

A spokesman for Police Scotland said: "We are aware of these events and they will be policed appropriately."

The response comes amid rising tensions in London, where fears were raised that similar demonstration could turn violent after football fans pledged to confront anti-Thatcher protesters in Trafalgar Square. Members of the so-called Maggie's Good Riddance Party are also planning a public protest outside St Paul's Cathedral on the day of Baroness Thatcher's funeral on Wednesday by turning their backs as the coffin passes through the streets of London.

Scotland Yard has made it clear it is monitoring social network sites for any forewarning of organised demonstrations and has stressed that, while people have a right to protest, unlawful disruption will be dealt with firmly. Thousands of police officers are expected to be on duty on the day of the funeral.

From 6pm today, thousands have vowed to celebrate the death of Baroness Thatcher in Trafalgar Square, scene of the poll-tax riots of 1990. Anarchist groups are believed to be behind the event. Demonstrators are said to be planning to hang an effigy of the former PM.

However, supporters from Millwall FC are due to travel back through the UK capital this evening after watching their team in the FA Cup semi-final at Wembley. One Millwall fan tweeted: "To all you protesting on Sat at Trafalgar Sq about Thatcher, be warned Millwall in town and in force."

Another Twitter-user wrote: "The Commies are having a party to celebrate Thatcher dying at Trafalgar Sq Saturday. 30k Millwall fans will be about too in London that day."

Boris Johnson, the London mayor, made it clear the authorities were prepared for any trouble. He stressed people had the right to lawful protest, but added: "What they can't do is use the death of an elderly person to begin riot or affray or that sort of thing. So we're getting ready for all that."

He added: "The police are obviously going to be making sure that if people do break the law, they will be properly dealt with."

Mr Johnson also made an appeal for people to behave, adding: "You have the perfect right to express your feeling, but bear in mind this is fundamentally about the death of an 87-year-old woman, her family are still mourning and you should think of that too."

Last night, David Hopper, general secretary of the Durham Miners' Association, said miners from the north-east of England would be among today's protesters. "She destroyed our communities, she destroyed our villages, she has destroyed our pits and she tried to destroy our dignity," he said.

"Her reign was a disaster for the mining communities."

Today's event in Trafalgar Square has gained a high profile thanks to Facebook groups and seems, at present, to be the main focus for vocal protest rather than the day of the funeral itself. While Maggie's Good Riddance Party claimed it would hold a "right jolly knees-up" outside St Paul's Cathedral on Wednesday, anti-capitalist campaigners appear not to have any clear plans to disrupt the funeral.