Lauren Booth, the sister-in-law of Tony Blair, was one of seven Britons among 44 civilian activists that set sail from Cyprus today, on a mission to break Israel’s blockade of the Gaza Strip.

Wearing a “Free Gaza” neck charm and standing barefoot in the humid heat before boarding one of two wooden boats in Larnaca port, Ms Booth, a half-sister of Cherie Blair, said: “These boats should be loaded with diplomats from around the world wanting to pursue the rights they supposedly represent.”

She challenged Mr Blair in his role as the international special envoy to the Middle East to “show some guts” and visit Gaza Strip. “Lip-service to the suffering of the Gazans without witnessing it at first hand makes a mockery of his [Blair’s] role,” she told The Times.

An attempt by Mr Blair to visit Hamas-controlled Gaza last month postponed at the last minute because of security concerns, although his office insists he will try again.

Instead of dignitaries such as Mr Blair, the two Greek-flagged boats are packed with human rights activists from 14 countries.

The youngest is 22 and the oldest is Sister Anne Montgomery, an 81-year-old Catholic nun who is one of 10 Americans in the group. There are also three Palestinians and an Israeli Jewish peace activist.

The campaigners from the US-based Free Gaza Movement , which raised most of the $300,000 needed for the voyage from private donations, might appear to pose little challenge to Israel.

The activists insist they pose no threat. “The Israelis have cannon, machine-guns, warships, helicopters and jets. All we have are hearing aids and biodegradable balloons for Palestinian children,” Greta Berlin, one of the American organisers, told The Times.

Israel accepts that the activists are not a security threat but has warned them to stay clear of Gaza - without specifying what action its navy may take - because the territory is controlled by Hamas.

“We assume that your intentions are good but, in fact, the result of your action is that you are supporting the regime of a terrorist organisation in Gaza,” the Israeli Ministry of Foreign Affairs said in a letter this week to the Free Gaza Movement’s organisers.

Nevertheless, Israel is likely to find itself in a bind tomorrow afternoon when the boats are due to approach an Israeli-imposed special security zone in Gaza waters.

The activists say their primary aim is a human rights one, not to deliver humanitarian aid. “The most important thing we bring are our voices,” Ms Booth said of the “travelling peace camp”.

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