Three members of the Oireachtas have returned home after they were refused permission to leave Cyprus to join a flotilla bringing aid to Gaza.
The international flotilla, carrying 10,000 tonnes of aid, is expected to reach the coast tomorrow.
However, Israeli authorities have vowed not to allow the human rights activists break its blockade of the Palestinian territory.
Israel, which controls the waters around Gaza, put a blockade in place in 2007 when Hamas took control of region.
The six ships left international waters off Cyprus this morning but have no estimated time of arrival in Gaza.
Sinn Féin TD Aengus Ó Snodaigh - who was part of the Irish delegation - has said he believes Israel brought pressure on Cyprus to intervene.
Chris Andrews TD and Senator Mark Daly (both Fianna Fáil) are the other members of the Irish contingent.