Pro-Palestinian activists from 22 countries plan to set sail in an international flotilla for Gaza from the coast of Crete on Thursday or Friday, organisers said Monday.

¨Thursday or Friday, nine or 10 boats should meet up in the Libyan Gulf,¨ Vaguelis Pissias, one of the Greek organisers of the flotilla, said at a press conference with representatives from the international organisations involved.

¨We really hope that despite the pressure from Israel and other countries, the Greek authorities are not going to stop us leaving," he added.

Organisers of the ¨Freedom flotilla¨ complained that the Greek authorities were creating ¨administrative obstacles¨ amid pressure from Israel to stop the campaigners from attempting to defy the five-year blockade of the Gaza Strip.

The departure has also been complicated by local politics, with transport strikes planned for this week as frustrated Greeks protest against harsh austerity reforms being voted on by the government of the debt-ridden country.

Several of the boats taking part -- including two cargo ships carrying three thousand tonnes of aid such as medicines and cement -- will set off from Greek ports, while others plan to join them out at sea, organisers said.

On Monday, Israel's security cabinet ordered its marines to prepare to stop the international flotilla from entering Gaza, but said they should avoid confrontation with the activists on board.

Despite warnings from the United States, France and Greece not to take part, 350 activists including artists, writers and Swedish, French, Norwegian and Spanish members of parliament, are hoping to draw attention to Gaza's plight.

A similar operation in May last year ended in violence when Israeli commandos seized the flotilla's flagship, the Mavi Marmara, leaving nine dead.

This year, French, Italian, Irish, Spanish, Canadian and American boats plan to take part, as well as a Greek, Swedish and Norwegian ship and two cargo vessels, one of which has been organised by Palestinian refugees.

¨Israel can't tell European countries which boats can leave or not,¨ said Thomas Sommer-Houdeville, a representative for the French ship from the ¨A Boat for Gaza¨ group.

Ann Wright, a member of the US delegation on the Audacity of Hope boat, said: ¨We are here to defy US and Israeli policy... and resist Israel's diplomatic efforts to stop the flotilla.¨