Former model Bianca Jagger and singer Annie Lennox joined human rights campaigners today to call on American president elect Barack Obama to speak up against the Israeli bombardment of the Gaza Strip.
Former Mayor of London Ken Livingstone and the 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."
The press conference was called ahead of a demonstration tomorrow that is expected to see thousands of people rally along the Embankment in London before marching to Trafalgar Square to demand an immediate end to the Israeli attacks.
Annie 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.
"How was this going to be the solution to peace?"
Comedian Alexei 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."
Also present at the press conference were the writer Tariq Ali, Lib Dem MP Sarah Teather, Labour MP Jeremy Corbyn and Respect MP George Galloway.
Over 400 Gazans have been killed and some 1,700 have been wounded since Israel began its aerial campaign on Saturday, Gaza health officials said.
The UN said the death toll in Gaza included more than 60 civilians, 34 of them children.
Three Israeli civilians and one soldier have also died in rocket attacks that have reached deeper into Israel than ever before, bringing one eighth of Israel's population within rocket range.
Israel launched the offensive after more than a week of Palestinian rocket fire that followed a six month truce.
An Israeli military spokesman announced yesterday that preparations for a ground operation were complete.
The demonstration is the culmination of days of smaller protests around the country and outside the Israeli Embassy in Kensington, central London.
Another demonstration outside the Egyptian Embassy in London is planned.
More than 30 organisations, including the British Muslim Initiative and the Stop the War Coalition have joined forces to organise the protest.