Anti-nuclear campaign group Trident Ploughshares said its activists had cut through a perimeter fence at Prestwick Airport, near Glasgow, on Monday and boarded a US plane to search for evidence of arms shipments to Israel.

David Mackenzie, a spokesman for the group said "security was lax" at the airport, making it easy for Trident Ploughshares' "war crimes detectives" to board the aircraft in the early hours. 

The group said the airport has been used by chartered cargo planes to carry US-made bunker-busting bombs to Israel as the war in Lebanon continues.

"We want to underline the fact that by colluding with the US  supplying Israel with bombs, Britain is colluding in war crimes," he said, although no bombs were found on the plane and it was not known if it was bound for Israel.

Besides the three who boarded the plane, four others were  arrested on Sunday for breaching the Prestwick airport perimeter and running on to a runway.

All seven are to appear in court on Tuesday.

Bush apology

"We want to underline the fact that by colluding with the US  supplying Israel with bombs, Britain is colluding in war crimes," he said, although no bombs were found on the plane and it was not known if it was bound for Israel.

David Mackenzie spokesman, Trident Ploughshares

Last month, a stopover at Prestwick of US flights carrying missiles to Israel sparked intense criticism in Britain.

George Bush, the US president, apologised for the flights' stopping without declaring the cargo they were carrying to Tel Aviv, the office of Tony Blair, the British prime minister, said.

Blair has denied that Britain has acted inappropriately and dismissed critics who have called for a ban on US military aircraft landing on British airfields.

About 70 protesters, including members of Scotland's Lebanese community, chanted anti-war slogans outside the airport's entrance last week to coincide with the expected arrival of two more weapons flights to Israel.