Hamas security officers patrol the waters off Gaza on Sunday while waiting for a flotilla of pro-Palestinian activists on six ships. (AP Photo/Hatem Moussa)Israeli warships attacked at least one of six ships carrying pro-Palestinian activists and aid for blockaded Gaza, killing at least two and wounding an unknown number of people on board, Middle Eastern news agencies reported early Monday.

A later report by an Israeli television station said the death toll may have reached 16.

The Israeli military denied that its forces attacked the ships, which were in international waters, but said they would enforce the decision to keep them away from Gaza.

However, an Israeli cabinet minister voiced regret for deaths aboard Gaza aid ships seized by Israel's navy on Monday, the first official acknowledgement that the incident had turned fatal.

"The images are certainly not pleasant. I can only voice regret at all the fatalities," Trade and Industry Minister Binyamin Ben-Eliezer told Israel's Army Radio.

Captain wounded

The al-Jazeera satellite network reported by telephone from the Turkish ship leading the flotilla that Israeli naval forces fired at the ship and boarded it, wounding the captain. The Turkish NTV network also reported an Israeli takeover with gunfire, and at least two people were killed.

The al-Jazeera broadcast ended with a voice shouting in Hebrew, "Everybody shut up!"

A Turkish website showed video of pandemonium on board one of the ships, with activists in orange life jackets running around as some tried to help an apparently unconscious activist.

The reports came just after daybreak, with the flotilla still well away from the Gaza shore. Israel had declared it would not allow the ships to reach Gaza.

The head of the Gaza Hamas government, Ismail Haniyeh, called "on the secretary-general of the UN, Ban Ki-moon, to shoulder his responsibilities to protect the safety of the solidarity groups who were on board these ships and to secure their way to Gaza," Haniyeh told The Associated Press.

On Sunday, Huwaida Arraf, one of the organizers, said the six-ship flotilla began the journey from international waters off the coast of Cyprus on Sunday afternoon after two days of delays. She said they expected to reach Gaza, about 400 kilometres away, on Monday afternoon, and that two more ships would follow in "a second wave."

"We fully intend to go to Gaza regardless of any intimidation or threats of violence against us," she said. "They are going to have to forcefully stop us."

Israeli frigates dispatched

After nightfall Sunday, three Israeli navy missile boats left their base in Haifa, steaming out to sea to confront the flotilla. Two hours later, Israel Radio broadcast a recording of one of the missile boats warning the flotilla not to approach Gaza.

"If you ignore this order and enter the blockaded area, the Israeli navy will be forced to take all the necessary measures in order to enforce this blockade," the radio message continued.

The al-Jazeera satellite channel reported that the ships changed course to try to avoid a nighttime confrontation, preferring a daylight showdown for better publicity.

The flotilla is trying to draw attention to Israel's three-year blockade of the Gaza Strip. The ships are carrying items that Israel bars from reaching Gaza, such as cement and other building materials.

Israel and Egypt imposed the blockade on Gaza after Hamas militants violently seized control of the territory in June 2007.

Israel says the measures are needed to prevent Hamas, which has fired thousands of rockets at Israel, from building up its arsenal. But UN officials and international aid groups say the blockade has been counterproductive, failing to weaken the Islamic militant group while devastating the local economy.

At Gaza's tiny port, Hamas officials, activists and foreign nationals prepared to welcome the flotilla, bobbing aboard dozens of small boats decorated with the flags of the countries of the pro-Palestinian activists.

With files from Reuters