Police warn of mass arrests at Palestine Action protest

The controversy over the ban on Palestine Action deepened yesterday as police warned of mass detentions if a demonstration that could attract more than 1,000 people carrying placards expressing support for the group went ahead this weekend.

- Ben Quinn Rajeev Syal Vikram Dodd

The Metropolitan police made clear it would arrest anyone breaking terrorism laws and Downing Street urged people not to attend.

In a further challenge to the ban on Palestine Action, 300 left-leaning Jewish figures including the director Mike Leigh and the author Michael Rosen will tell the prime minister in a letter today that the decision is "illegitimate and unethical".

Campaigners from the pressure group Defend Our Juries plan to descend on Westminster on Saturday carrying placards and posters expressing support for the group.

They are protesting against the home secretary Yvette Cooper's decision to ban the organisation last month after activists caused an estimated £7m of damage to jets at RAF Brize Norton.

Defend Our Juries is asking those taking part to hold up signs saying "I Oppose Genocide, I Support Palestine Action".

More than 200 people have already been arrested in response to the proscription last month.

A Met police spokesperson said the organisers of the protest were attempting to put the overcrowded criminal justice system under further pressure.

"We are aware that the organisers of Saturday's planned protest are encouraging hundreds of people to turn out with the intention of placing a strain on the police and the wider criminal justice system," they said. "The Met is very experienced in dealing with largescale protests, including where the protest activity crosses into criminality requiring arrests.