Viva Palestina will no longer sponsor flotillas to Gaza because it conflicts with the group's charitable status. But the UK-based group, whose founders include former Respect MP George Galloway, said it would continue to support future flotillas.

VP's latest newsletter said: "A number of supporters are asking about the second flotilla to Gaza. VP was represented on the first flotilla on the Mavi Marmara, which was so brutally attacked by Israeli forces.

"The trustees have decided that VP cannot be a sponsor of the second flotilla, given our charitable status, though we are, of course, entirely supportive of the aim of breaking the siege."

Spokesman Rob Hoveman said: "The reasons the trustees cannot give VP's support to the flotilla is that the risk of attack, as evidenced by the Israelis' preparedness to kill nine aid workers last year, means that the relevant British authorities would be likely to consider the aid mission too hazardous for a British registered charity."

But to mark the first anniversary of the shootings on the Mavi Marmara, where nine activists died in a confrontation with Israeli forces, a ship is leaving Britain in May, under the aegis of a new organisation, Britain 2 Gaza. This is an umbrella group for five British campaign groups; Friends of Al Aqsa, the British Muslim Initiative, the Palestine Solidarity Campaign, Stop the
War Coalition and the Palestinian Forum of Britain.

A spokeswoman for the Charity Commission said: "We have not advised Viva Palestina that they must cease sponsoring the flotilla, but it is the responsibility of the charity's trustees to make sure they comply with charity law."

One of the charity's trustees, who made the decision, was a former aide to Mr Galloway, Kevin Ovenden. He was the group's representative on the Mavi Marmara. He was later arrested in Israel and deported.