A UN rapporteur Thursday slammed a highly anticipated UN report set to back an Israeli commando raid of a 2010 flotilla seeking to break the Gaza blockade which left nine people dead.

"The United Nations Special Rapporteur on the Right to Food, Prof. Olivier De Schutter, has received a draft of this report and he firmly opposes its conclusions," De Schutter's office said in a statement.

He was preparing "a statement where he denounces the conclusions" of the report which the UN chief is expected to release on Friday, it added.

"Tomorrow, the United Nations Secretary General Ban Ki-Moon will release a statement supporting the legality of the Israeli intervention against the 2010 "Gaza Freedom Flotilla," the statement said.

"According to Olivier De Schutter, the blockade and the Israeli intervention clearly violate international law and the human right to food," it added.

Last year's bloody May 31 showdown when Israeli commandos raided a six-ship flotilla leaving nine Turkish activists dead triggered global outrage, amid accusations that Israel had been too heavy-handed in its actions.

The news of the release of the UN report came as Israel battened down the hatches at its main airport awaiting hundreds of pro-Palestinian protesters after a new flotilla bid to ship aid to the Gaza Strip was scuttled.

Organizers of the 10-ship aid flotilla which activists were hoping to sail to Gaza in defiance of the blockade said the lone boat to sneak out of a Greek port was caught Thursday by the coast guard in Crete.

In a new move though, 600 or so activists were jetting in by air planning to spend a week visiting Palestinian families, with organizers saying they have "totally peaceful intentions."

But Israeli authorities appeared to be gearing up for a confrontation, with hundreds of police on standby around the airport.

"There is a large police presence in and around the airport to prevent any disturbances," police spokesman Micky Rosenfeld told AFP on Thursday.