DUBLIN/JERUSALEM (Reuters) - Activists vowed on Tuesday to try to break the Israeli blockade of Gaza with another ship, and an Israeli officer pledged to halt it, setting the stage for a fresh confrontation after Monday’s deadly clash.

The MV Rachel Corrie, a converted merchant ship bought by pro-Palestinian activists and named after an American woman killed in the Gaza Strip in 2003, set off Monday from Malta, organizers said. “We are an initiative to break Israel’s blockade of 1.5 million people in Gaza. Our mission has not changed and this is not going to be the last flotilla,” Free Gaza Movement activist Greta Berlin, based in Cyprus, told Reuters.

Irish Prime Minister Brian Cowen described the vessel as Irish-owned and said it should be allowed to finish its mission. The ship was carrying 15 activists including a northern Irish Nobel Peace laureate.

“The government has formally requested the Israeli government to allow the Irish-owned ship ... to be allowed to complete its journey unimpeded and discharge its humanitarian cargo in Gaza,” Cowen told parliament in Dublin.

An Israeli marine lieutenant, who was not identified, told Israel’s Army Radio his unit was prepared to block the ship.

“We as a unit are studying, and we will carry out professional investigations to reach conclusions,” the lieutenant said, referring to Monday’s confrontation in which his unit shot nine activists aboard a Turkish ferry.

“And we will also be ready for the Rachel Corrie,” he added.

Passengers include Northern Irish Nobel peace laureate Mairead Corrigan-Maguire and Denis Halliday, an Irish former senior UN diplomat, and several other Irish citizens.

Irish Foreign Minister Micheal Martin told parliament he had spoken with Halliday Tuesday afternoon.

“We will be watching this situation very closely -- as indeed will the world -- and it is imperative that Israel avoid any action which leads to further bloodshed,” Martin said.

Israel’s Army Radio reported that the ship would reach Gazan waters by Wednesday, but activist Berlin said it might not attempt to reach Gaza until early next week.

“We will probably not send her till (next) Monday or Tuesday,” she said of the 1,200 ton cargo ship. The Israeli navy stormed aboard a Turkish ferry leading a six-ship convoy Monday, killing nine people in what authorities said was self-defense but sparking a world outcry, a crisis in diplomatic relations with Turkey and condemnation from the United Nations Security Council.

The Rachel Corrie was carrying medical equipment, wheelchairs, school supplies and cement, a material Israel has banned in Hamas-ruled Gaza, organizers said.

Mark Daly, a member of Ireland’s upper house of parliament who had been due to join the convoy but was refused permission to leave Cyprus, told Reuters in Dublin that the ship had fallen behind the rest of the convoy because it was slower.

Passengers aboard it had heard about the attacks but decided not to turn back, he said.

“After having a discussion among themselves about what to do, they decided to keep going,” Daly said.