Israel's Defence Minister Ehud Barak has voiced concern that once-stalwart ally Turkey could share Israeli intelligence secrets with Iran, revealing a deep distrust as Ankara's regional interests shift.

The leaked comments by Barak cast doubt on how much Israel is willing or able to reconcile with Turks outraged at its navy's killing of nine of their compatriots aboard an aid ship that tried to run the Gaza Strip blockade on May 31.

Until relations soured, Turkey had been the Muslim power closest to the Jewish state, a friendship largely based on military co-operation and intelligence sharing.

In a closed-door briefing to activists aligned with his centre-left Labour Party at a kibbutz near Jerusalem on July 25, Barak still called Turkey a 'friend and major strategic ally'.

But he described Hakan Fidan, the new head of its National Intelligence Organisation, as a 'friend of Iran'.

'There are quite a few secrets of ours (entrusted to Turkey) and the thought that they could become open to the Iranians over the next several months, let's say, is quite disturbing,' he said in a segment of the speech broadcast by Army Radio.

Barak was speaking in the context of past Israeli-Turkish intelligence co-operation, an audience member told Reuters on Monday. An Israeli defence official said the event was private and that the aired recording of Barak had not been authorised.

Appointed in May, Fidan was previously a foreign policy adviser to Prime Minister Tayyip Erdogan, whose AK Party has roots in political Islam and has often censured Israel.

Political sources in Ankara said that Fidan, a former envoy to the UN nuclear watchdog, was also involved in a Turkish- and Brazilian-brokered compromise proposal - received coolly in the West - to curb Iran's controversial uranium enrichment.

Israel has hinted at last-ditch military strikes to deny the Iranians the means to make a nuclear bomb - a threat boosted by its 2007 air raid on an alleged atomic reactor in Syria, during which Israeli warplanes briefly flew over Turkish territory.

The Erdogan government was angered by that incursion and has pointed to Israel's own assumed nuclear arsenal. Such positions have rallied Arabs and Muslims around Turkey, a Nato member.

Ali Nihat Ozcan of the Ankara-based TEPAV think tank saw in Barak's remarks an effort at 'psychological pressure' on Turkey.

'If somebody like Barak has voiced such concerns, it shows that there's a blockage in the intelligence sharing channels,' he said.

'It's understood that there is a paranoia that Turkey could share with Iran what it could have shared with Israel before, regarding Iran's nuclear programme.'

Ankara has not commented publicly on the state of its intelligence ties with Israel. But some Turkish commentators have looked askance at media reports of Israeli collaboration with Kurds in northern Iraq, given their suspected ties to Turkey's separatist Kurdish guerrilla group PKK.

By contrast, Israel's Mossad spy agency was widely reputed to have helped Turkey to capture PKK leader Abdullah Ocalan in 1999, though then-Mossad chief Efraim Halevy denied involvement.

There has also been ridicule in Turkey of an Israeli inquiry into the interception of the pro-Palestinian aid ship Mavi Marmara, which faulted military intelligence for not anticipating passengers' resistance to the naval boarding party.

Marines shot dead nine Turks in the ensuing brawl on deck, an action Israel has justified as self-defence.

Turkey, which withdrew its ambassador and suspended joint military exercises with Israel in protest at the bloodshed, has demanded an apology and a wider international investigation.-Reuters