Geneva: A UN human rights expert said on Monday that the international community should hold Israeli decision-makers accountable for the deaths that occurred when Israeli forces stormed an aid flotilla.

The UN Special Rapporteur for the Occupied Palestinian Territories, Richard Falk, called for a worldwide boycott and sanctions against Israel.

He "urged.. the international community to bring to justice those responsible for the killing of some 16 unarmed peace activists," the UN said in a statement.

Falk added: "It is essential that those Israelis responsible for this lawless and murderous behaviour, including political leaders who issued the orders, be held criminally accountable for their wrongful acts."

"Israel is guilty of shocking behaviour by using deadly weapons against unarmed civilians on ships that were situated in the high seas where freedom of navigation exists, according to the law of the seas."

Between 10 and 19 activists were reported killed before dawn on Monday when Israeli navy commandos stormed the Gaza-bound flotilla organised by pro-Palestinian activists, sparking international outrage.

Israeli military officials and commandos involved in the operation said they had only responded with force after they were attacked by the ships' passengers with knives, clubs and even live fire.

Falk urged global action in response to the interception.

"It is time to insist on the end of the blockade of Gaza," he said.

"The worldwide campaign of boycott, divestment, and sanctions against Israel is now a moral and political imperative, and needs to be supported and strengthened everywhere."

The UN rapporteur has frequently clashed with Israeli authorities over their policies towards the Palestinians and sharply criticised human rights violations, while Israel rejects his mandate as biased.

In December, Falk said major powers had failed to end Israel's three year old blockade of the Gaza Strip and called for a "credible threat" of economic sanctions against Israel.