Jerusalem (AFP) - An emerging deal between Iran and world powers won't prevent the Islamic republic from reaching nuclear weapon capacity, Israeli Prime Minister Benjamin Netanyahu said Tuesday, noting Arab states shared his concern.

"I know I'm often portrayed as the nuclear party pooper, and that would be okay if I was the only voice against the impending deal with Iran," he said at a security conference at Herzliya near Tel Aviv.

"But I speak with quite a few with our neighbours, more than you think. And I want to tell you that nobody in this region believes this deal will block Iran's path to the bomb.”

Netanyahu's remarks came as a June 30 deadline looms for a deal that would row back Iran's nuclear programme in return for relief from sanctions, which Israel has long opposed, causing friction with the White House.

In a possible move to allay concerns, chairman of the US Joint Chiefs of Staff General Martin Dempsey on Tuesday held meetings with his Israeli counterpart as well as Defence Minister Moshe Yaalon, who praised the close coordination between the allies.

"Israel and the IDF (Israeli Defence Forces) have no greater friend on the face of the earth than the US military," Dempsey told Israeli military chief of staff Lieutenant General Gadi Eisenkot.

Dempsey's visit, his last to Israel as the top US military officer, came as a report emerged that CIA chief John Brennan made a "secret" visit to Israel last week to discuss the Iran deal

According to a report in Israel's Haaretz newspaper, Brennan met his counterpart Mossad chief Tamir Pardo and other intelligence officials, as well as Netanyahu.

They discussed the emerging Iran deal and Tehran's "subversive" activities around the Middle East, Haaretz said.

Netanyahu's staunch opposition to any agreement with Iran has helped bring his relations with US President Barack Obama to an all-time low.

In March, the Israeli premier controversially took his campaign to the US Congress, calling on lawmakers to block any deal between the powers and the Jewish state's arch-foe.