ATHENS/NICOSIA: A Greek-flagged vessel carrying peace activists, doctors and medical supplies for the embattled Gaza Strip was forced to turn back to a Cyprus port yesterday after Israeli warships threatened to open fire, reports said.

The Arion, whose passengers included peace activists from the US “Free Gaza” group, doctors, aid workers and European parliamentarians, had set sail from Cyprus a day earlier after a two-day delay due to mechanical problems.

They hoped to break through the Israeli blockade and enter Gaza carrying relief supplies for Palestinians in Gaza, but activists said they were returning to Cyprus after an overnight encounter in international waters, where, they said, Israeli ships threatened to open fire.

The 21 passengers, which also included parliamentarians from Greece, Spain and Belgium, were intercepted about 160 kilometers northeast of Gaza. It is the second attempt by activists to enter the Gaza Strip in less than a month after a similar effort to deliver aid was thwarted by Israel in December.

The Free Gaza group has made five deliveries of aid by boat to Gaza since August, defying a blockade imposed by Israel when Hamas won control of the territory in June 2007.

Greece strongly protested to Israel after its navy turned back the boat, the Foreign Ministry said in Athens yesterday. Greece called on the Israeli authorities to ensure the safety of those on the boat, which was flying Greek colors, said the ministry.

Theodoros Dritsas, a left-wing Greek deputy on the boat, denounced Israel’s intervention as “piracy.” Karin Pally, the movement’s coordinator, said the “The Spirit of Humanity,” had been surrounded by Israeli naval vessels while still in international waters.

“Apparently, the boats threatened to fire on them or stop them by any means, and the decision was taken to return to (the Greek port) of Larnaca,” she said. The boat was carrying several tons of medical supplies.

“This is an unacceptable act of piracy,” said Dritsas, one of 12 Greeks among the 21 people on the boat. “The Israeli Navy had no right to intervene in international waters.”

The last attempt by the movement to beat the Israeli blockade, on Dec. 30, also failed after their boat was also turned back by an Israeli patrol vessel. On that occasion, the Free Gaza Movement said Israeli vessels had deliberately rammed the boat.

The vessel was due back in the southern Cyprus port later yesterday. “Everybody on board is safe.” Passengers said it was a deliberate ramming.

Israel’s Transport Ministry, in a statement, had called the attempt to reach Gaza “provocative and risky.” British surgeon Sonya Robbins described as a “massacre” the death toll of Gaza’s civilians since Israel unleashed its war on the Islamist movement Hamas on Dec. 27.

More than 1,000 people have died, many of them children, and more than 4,850 people have been wounded, according to Palestinian emergency services.

“It is not far off from a war crime. It’s a totally inappropriate action to Palestinian fireworks (rockets). The Palestinians have a right to defend themselves, not only Israel,” Robbins told AFP before the boat set off on Wednesday.

Earlier on Wednesday, the Israeli Navy intercepted an Iranian ship loaded with medicine, food and clothing destined for Gaza and forced the vessel to Egypt instead.

The head of the humanitarian aid group sponsoring the ship, Ahmad Navabi, said in comments aired on television Wednesday that the Israeli Navy approached the cargo ship, Shahed, just 30 kilometers off the coast of Gaza at dawn Wednesday, and ordered it to turn back.

“An Israeli warship approached our cargo ship and warned us not to approach Gaza. We could see the lights at Gaza coast. We were forced to change route toward an Egyptian port,” Navabi said.

Israeli military officials said the ship was prevented from reaching Gaza as part of a general naval blockade meant to prevent weapons smuggling, and not due to the boat’s Iranian origins.

The Israeli officials said an Israeli naval ship approached the vessel, conveyed by radio the message of the blockade of Gaza, and told the crew they would not be allowed in. There was no clash, the Israeli officials said.

Iranian state television broadcast what they said was a radio exchange between the Israeli navy and the Iranian ship in which the Israelis said: “Gaza is closed. Leave the area immediately.” Iran’s Foreign Minister Manouchehr Mottaki said later Wednesday that Iran will do what it can to get the ship to Gaza, state television reported.