At least 16 people have been killed and 30 injured after Israeli troops stormed a convoy of six ships carrying activists and aid supplies to Gaza.

According to reports, the confrontation took place in international waters 80 miles off the Gaza coast when armed forces boarded the vessels overnight and clashed with some of the 600 protesters on board.

A Guardian report says top writer Henning Mankell and many top journalists were there when the attack happened.

A spokesman for Greta Berlin, one of the ships, accused Israeli troops of indiscriminately shooting at "unarmed civilians".

"How could the Israeli military attack civilians like this? Do they think that because they can attack Palestinians indiscriminately they can attack anyone?" The Telegraph quoted Berlin, as saying.

"We have two other boats. This is not going to stop us," he added.

Meanwhile, Israeli Trade and Industry Minister Binyamin Ben-Eliezer has issued a statement.

"The images are certainly not pleasant. I can only voice regret at all the fatalities," Ben-Eliezer said.

The ships, carrying 10,000 tonnes of aid, had left international waters off the coast of Cyprus on Sunday and were expected to arrive in Gaza later on Monday.

Israel had earlier said that it would stop the boats, calling the campaign a "provocation intended to delegitimise Israel".

An economic blockade was imposed on Gaza by Israel after the strip was taken over by the militant group Hamas [ Images ] in 2007.

It has allowed some food and medical supplies through, but has prevented large-scale rebuilding following the bombardment and invasion in 2008-09.

Around 10,000 Turks are marching from Israel's Consulate in Istanbul toward the city's main square, shouting slogans denouncing Israel after 10 pro-Palestinian activists were reported killed and dozens wounded by Israeli forces.

Greece has withdrawn from joint military exercises with Israel in protest at the attack on the Gaza flotilla. Athens has also barred the head of the Israeli airforce from flying to Greece.

In Europe, France has condemned the incident, saying it has shocked the country.

The UN's rights chief Navi Pillay said she was "shocked" at the violence of the raid.