Tens of thousands of protesters are due to voice their anger at the Gaza bombing blitz in a series of rallies across the UK.
Up to 20,000 people - including the singer Annie Lennox and Respect MP George Galloway - are expected to march along the Embankment in London before walking to Trafalgar Square to call for an immediate end to the Israeli attacks.
The demonstration is the biggest of at least 18 organised across the country.
Former model Bianca Jagger and singer Lennox have backed the protests, calling on American President-elect Barack Obama to speak up against the bombardment.
Other rallies will take place at Blytheswood Square, Glasgow; Bedford Square, Exeter; Princes Street, Edinburgh; Bristol city centre; Bold Street, Liverpool; Norwich Forum; Portsmouth’s Guildhall Square; Queen Victoria Square, Hull; Tunbridge Wells town centre; Leeds Art Gallery; All Saints Park, Manchester; Grey’s Monument, Newcastle; Castle Square, Swansea; St Sampson’s Square, York; Morrisons, Caernarfon; Bradford city centre; and Sheffield town hall.
Former mayor of London Ken Livingstone and comedian Alexei Sayle also added their support to the campaign to end the violence.
Speaking at a press conference in central London, Ms Jagger said: “I would like to make an appeal to President-elect Obama to speak up.
“People throughout the world were hopeful when he was elected and we must appeal to him to ask for the immediate cessation of the bombardment of the civilian population in the Gaza Strip.”
Lennox spoke of her shock at watching scenes of the bombing on television. She said: “A few days after Christmas I came downstairs, put the television on, and saw smoke pyres coming from buildings and I was shocked to the core because I was thinking as a mother and as a human being.”
Comedian Sayle said he was speaking out because it was important for Jewish voices to be heard. He said: “I want to feel proud of Israel, I want to be proud of my people but I am ashamed.”