Police in London are on stand-by for the biggest strike in years as thousands of public sector workers prepare to stage a walk-out tomorrow.

All police leave has been cancelled for tomorrow as it is feared that the 24-hour strike by teachers, civil servants and other public sector workers may cause major disruption in the capital.

Although the majority of marchers are expected to protest peacefully, police fear that a small number of activists may cause trouble on the marches. 

Anarchist groups have called their members to come out onto the streets tomorrow.

Only three schools in Camden – the borough worst-hit by the strikes – will open tomorrow.

Passengers travelling through Gatwick and Heathrow airports are being warned to expect delays at passport control as immigration and customs staff are also on strike.

Roads around the Palace of Westminster will be closed.

Picket lines will be set up at the House of Commons, Scotland Yard, 999 call centre, courts and tax offices.

The main protest will start at Lincoln's Inn Fields in Holborn at 11am and will finish at the Methodist Central Hall in Westminster.

Around 750,000 members of four trade unions are striking tomorrow across the UK in a row over pensions.

But Deputy Prime Minister Nick Clegg has told union bosses that the Government would not give in to strike pressure.

Clegg said: "We are absolutely adamant in government that this issue can only and must only be resolved through dialogue and discussion, not through strikes and conflict," he said. He added: "I'm acutely aware that millions of people are asking themselves what's going to happen tomorrow? Are they you going to be able to send their kids to school? How are they going to get to work? Are they going to be able to get away on holiday?

"And it seems to me that the strikes tomorrow are not going to help those millions of people, aren't going to help the millions of members of the trade union movement and they are not going to help the country."