"Let me be clear that the situation in Gaza has to change... Gaza cannot and must not be allowed to remain a prison camp," he said in a speech to a business association during a visit to Turkey.

Speaking later after talks with Turkish Prime Minister Recep Tayyip Erdogan, Cameron defended his harsh description, saying that "even though some progress has been made we're still in a situation where it's very difficult to get in, it's very difficult to get out...

"We've long supported lifting the blockade of Gaza," he said.

Cameron however acknowledged Israel's security concerns, pointing to rocket attacks from Gaza, run by the radical Palestinian group Hamas, on Israel.

"We both share the view that direct talks (between Israel and the Palestinians) is the right answer," he said, referring to Erdogan.

The prime minister also called on Turkey to repair ties with Israel after an Israeli raid on Gaza-bound aid ships left nine Turkish activists dead on May 31.

"Turkey has been a good friend of Israel in the past. I very much hope Turkey can go on being a friend of Israel because... as a friend of Israel, Turkey will maximise her influence over what needs to happen in terms of those direct talks," he said.

The raid on the aid flotilla plunged already strained ties between the one-time allies into deep crisis. Ankara has urged the Jewish state to apologise, compensate the families of the dead and lift the blockade of Gaza.

"Turkey's relationships in the region, both with Israel and with the Arab world, are of incalculable value," Cameron said.

"And I urge Turkey and Israel not to give up on their friendship," he added.

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