* Mossad chief cites shared regional concern over Iran
* In rare speech, says Mossad pursuing Arab peace links
* Reaffirms determination to block Iranian nuclear bomb
By Dan Williams
HERZLIYA, Israel, July 1 (Reuters) - Israel and U.S.-aligned Arab countries have what might be a unique chance to forge a regional peace deal given their shared worries about Iran, the chief of Israel's Mossad spy service said on Monday.
In a rare public appearance, Joseph (Yossi) Cohen said his agency had formed a task force designed to spot peacemaking opportunities in a region where only two Arab states, Egypt and Jordan, have full ties with Israel.
"The Mossad today espies a rare opportunity, perhaps for the first time in Middle East history, to arrive at a regional understanding that would lead to a comprehensive peace accord," he told the Herzliya Conference, an annual international security forum near Tel Aviv.
"Common interests, the fight against rivals such as Iran and Jihadist terrorism, the close relations with the White House and channels of communication with the Kremlin all combine to create what might be a one-time window of opportunity," Cohen said.
The United States convened Arab and other dignitaries in Bahrain last week to encourage investment in the Palestinian economy that might help renew peace talks with Israel.
The Palestinians, seeing a pro-Israel bias in the Trump administration and a ruse to deny them their goal of full statehood, boycotted the Manama meeting. Israel, which sent only a non-official delegation, saw in the event a chance to bolster its wider ties to the Arab world.
Washington hopes wealthy Gulf states will bankroll a U.S. plan for trade and investment, which expects donor nations and investors to contribute $50 billion to Palestinian and neighbouring Arab state economies.
But the Palestinians and many Arabs in the region dismissed the economic plan as pointless without a political deal, a goal that repeatedly eluded previous peace efforts.
Cohen, whose speech alluded to the Palestinians only in the context of threats against Israel from the armed factions, said many Arab countries "cannot stand Iran's thuggish behaviour".
He cited Iran's nuclear programme, assistance for guerrillas in Lebanon, Syria, Yemen and elsewhere and alleged responsibility for a recent spate of sabotage strikes on oil tankers in the Gulf. Iran denies any role in those incidents.
Cohen said Israel's warming of relations with Oman, which Prime Minister Benjamin Netanyahu visited last October, followed "a lengthy covert effort by the Mossad" to seek out closer ties.
He pointed to what he termed "an expanding group of responsible, serious countries" - which he did not name - in the region that have "open channels of communication with Israel", but no formal relations, and cooperate with it in various ways.
With Iran threatening to exceed the limitations of a 2015 deal capping its nuclear projects, and which the United States withdrew from last year, Cohen reaffirmed Israel's policy that it would not allow its arch-foe to get a bomb.
"The Mossad or the State of Israel did not sign the nuclear deal (and) will do everything to ensure that Iran will never have nuclear weaponry," he said.
On Monday, two sources told Reuters Iran had breached the limit of its enriched uranium stockpile set in the 2015 deal, defying a warning by European co-signatories to stick to the deal despite U.S. sanctions.
Iran denies ever seeking to acquire a nuclear bomb.
"Currently, it's about uranium enrichment at a relatively low percentage, and in amounts that are not large. The threat is to step up enrichment and increase the amounts," Cohen said, before news of the enrichment breach.
"Just imagine what will happen if the material stockpiled by the Iranians becomes fissionable, at military-enrichment grade, and then an actual bomb. The Middle East, and then the entire world, will be a different place. Therefore, the world must not allow this to happen." (Editing by Jeffrey Heller, Editing by William Maclean)