An aid flotilla will leave for the Gaza Strip in the third week of June, just over a year after a similar flotilla was raided by Israeli forces, leaving nine people dead on a Turkish boat, activists say.
A coalition of pro-Palestinian groups, most of them based in Europe, announced the date after a meeting in Paris.
The unfolding plans for the new flotilla set up a possible confrontation with Israel, which has vowed to stop any attempt to breach its sea blockade of Gaza.
Activists had originally planned to depart on May 31, the anniversary of the botched Israeli commando raid, but the delayed departure appears at least partly related to Turkey's plans for parliamentary elections on June 12.
Turkish activists, who are in contact with the government but say they operate independently, had said they wanted to leave after the vote for fear any controversy could disrupt the election debate.
Turkish officials, who have stepped up criticism of Israel since the three-week war in Gaza that ended in early 2009, have indicated that the Turkish activists are free to sail from home waters.
The Freedom Flotilla coalition said Marseille, France, was one of various European departure points for the convoy, and that it welcomed "the recent addition" of a Swiss-German boat. It did not say how many boats were participating, but IHH, an Islamic aid group in Turkey, has said it expects the convoy to be at least twice as big as the one that attempted to reach Gaza last year.
Six ships set sail last year. This year's convoy includes the Mavi Marmara, the same Turkish vessel operated by IHH on which the activists died in the raid, and an American vessel named The Audacity of Hope, the title of a book by US President Barack Obama.
The coalition said organisers would head to Strasbourg, France, to seek the support of European parliamentarians.
Eight Turks and one Turkish-American died in the raid last year and seven Israeli soldiers were wounded. Each side accused the other of starting the violence. The incident drew world attention to the humanitarian situation in Gaza and plunged ties between former allies Israel and Turkey to a new low.