A coalition of activists said on Tuesday they would send a flotilla of ships to break Israel's siege of Gaza by the end of 2014, fours years after a similar campaign ended in a deadly raid by Israeli commandos.

"We plan to send the flotilla during 2014," the Freedom Flotilla Coalition, which includes activists from at least 10 countries, said in Istanbul.

The statement was made at a joint conference hosted by Turkish relief agency Humanitarian Relief Foundation (IHH), which sponsored the first flotilla of ships carrying aid to Gaza that was raided by Israeli commandos in 2010.

The group did not give a specific date or an estimate on how many vessels or people would participate.

The IHH, which many believe has close ties with the Turkish government, is one of the members of the coalition, which includes groups from Greece, Norway and Sweden.

"It is a reflection of the growing worldwide solidarity with the Palestinian people, from the US to Malaysia, from Scandinavia to South Africa," the Freedom Flotilla Coalition said.

The boats would sail at the same time from different ports around the world, carrying humanitarian aid as well as Palestinian commercial products, it added.

"We will try to form this flotilla with the aim of showing that international community cannot sit and look away when attacks on civilians and crimes against humanity are committed," said Canadian activist Ehab Lotayef.

He added that the coalition would not seek support from any government and there would not be any military escort.

Israel says it imposed its blockade on Gaza in 2007 to prevent weapons from reaching Hamas, the Islamic militant group that rules Gaza.

"We will commit ourselves to non-violence, but as long as the blockade is there, we will sail again and again," the group said.

In 2010, Israeli commandos stormed the Turkish-flagged Mavi Marmara, the largest ship in a flotilla dispatched by the IHH.

Nine Turks died in the raid and one more died in hospital this year after four years in a coma.

The assault on the ship in international waters sparked widespread condemnation and provoked a major diplomatic crisis between Turkey and Israel.

The flotilla will again include Mavi Marmara, but the initiative is "by no means encouraged by the Turkish government," the IHH deputy head Durmus Aydin told AFP.