Updated

ISTANBUL -- Pro-Palestinian activists on Monday marked the first anniversary of a deadly raid by Israel on a Turkish aid ship bound for the Gaza Strip by gathering on the deck of the same boat, refitted and preparing to sail for Gaza again next month.

An international coalition of activists said Egypt's removal of a 4-year-old blockade of the Gaza Strip last weekend will not affect their plans for a new flotilla, which will depart from various European ports in an attempt to breach Israel's sea blockade. Israel says the blockade stops weapons reaching Hamas militants, but activists describe restrictions on Gaza's 1.5 million residents as a human rights violation.

"The Gaza shore has to be free. That's why we are sailing there," said Vangelis Pisias, a Greek organizer, said at a news conference on the Mavi Marmara, a ferry that was boarded by Israeli commandos before dawn on May 31, 2010. Nine activists died in the botched commando operation, with each side accusing the other of starting the violence.

Pisias said the aid convoy would sail in "20 days," though IHH, the Islamic aid group that operates the Mavi Marmara, has said only that the third week of June was the target date for departure. That would allow Turkey to proceed with parliamentary elections on June 12 without fear of a possible confrontation at sea that would likely disrupt the electoral debate and distract the country's leadership.

Late Monday night, crowds marched to Istanbul's Taksim Square, a central plaza, to commemorate the nine slain activists with songs, speeches and prayers.

Israeli military officials have said troops have been training for months to intercept any flotilla, and plan to use different tactics this time. The officials refused to elaborate. They spoke on condition of anonymity because of the secrecy of the planning.

Last year's raid plunged ties between Israel and Turkey to a new low, and the Turkish government has said it will not block Turkish activists from setting sail in the Mavi Marmara from a dock on the Golden Horn, an inlet in Istanbul. Israel eventually released the vessel after seizing it in the raid, and on Monday workers in blue overalls checked lifeboats alongside a deck festooned with Turkish and Palestinian flags.

Turkey seeks an Israeli apology and compensation for the slain activists' families. Israel eased its land blockade of Gaza because of the international furor over the raid, but maintains that Iran-backed Hamas, which violently seized control of Gaza in 2007, seeks to smuggle in weapons for use against Israel.