Jerusalem - An international flotilla seeking to challenge Israel maritime blockade of the Gaza Strip is nearing its destination although its exact location is unknown, supporters said Saturday.

A three-vessel "Freedom Flotilla" left Palermo, Sicily, on July 21 and the first of them, the "Awda", or "Return" in Arabic, could arrive off the Gaza shore as early as Sunday, Pierre Stambul, co-president of the French Jewish Union for Peace said in an e-mail to AFP.

Israel begins work on Gaza sea barrier

Stambul, who is not aboard, said that about 40 activists from 15 countries, including two from France were taking part.

As in previous attempts to breach the blockade, the ships were expected to be stopped at sea by the Israeli navy and taken to an Israeli port.

A video report posted online Saturday from onboard one of the ships, by Richard Sudan of Iran's Press TV UK, said that one of the smaller vessels had dropped out with an unspecified "problem".

"So two boats are now currently making their way toward the Gaza Strip," he said.

Passengers, he said, included journalists, activists and at least one lawmaker.

"There's a Jordanian MP on the other boast, the Awda, and various activists from across Europe," he said, adding that the blockade challenge "is a gesture of solidarity to the Palestinians."

"There is also some medical aid on board, although the amount of medical aid is merely a gesture,' he added. "We're talking just a few boxes."

In 2010, Israeli commandos killed nine Turkish activists when they raided a six-ship flotilla trying to reach the Gaza Strip in defiance of the blockade. Another activist died years later.

The botched raid angered Turkey and saw it cut off ties with Israel until 2016.

Other attempts to run the Israeli blockade included a 2016 women's boat with 13 passengers including Nobel Peace Prize winner Mairead Maguire of Northern Ireland.

Their sailing boat was halted by the Israeli navy and taken to the Israeli port of Ashdod, about 30 kilometres north of Gaza and the women were detained before being deported.

Israel maintains its blockade to keep material it believes could be used for military purposes from entering the coastal enclave, run by the militant Islamic Hamas.