UN leader Ban Ki-moon said he expects Israel to attend an international conference on creating a Middle East nuclear-free zone he is aiming to hold this year in Helsinki.

"Israel will be invited and they should be there but nothing has been decided yet," Ban said late Wednesday, adding he had not raised the sensitive conference during talks with Prime Minister Benjamin Netanyahu in Jerusalem earlier.

Diplomats consider the presence of Israel and Iran would be crucial to the success of any conference, which was called for by the nuclear Non-Proliferation Review held in 2010.

Preparations are going ahead amid mounting Western concerns over Iran's nuclear programme. Western countries accuse Iran of seeking a nuclear weapon. Iran denies the charge. Israel is widely believed to have an atomic arsenal but refuses to confirm or deny its existence.

The UN secretary general, who has made nuclear disarmament one of his priority issues, told a small group of reporters that he was "actively consulting the parties concerned" in preparing the conference.

"Considering all the presidential elections in major countries we are looking at the possibility of convening this meeting at the later stage of this year," Ban said, refering mainly to the US election.

The UN leader named Finland's undersecretary of state for foreign affairs, Jaakko Laajava, in October to be the main conference planner.

"Nothing has been decided for the exact date," Ban said. "I have received an initial report from my facilitator (Laajava), but it is going to happen," the secretary general said.

Ban said Iran was one of the regional topics that he discussed with Netanyahu but gave no details.

Last week, the UN leader stepped up calls for greater international efforts to break the deadlock at the Conference on Disarmament in Geneva. He warned it could fail because of Pakistan's reluctance to discuss nuclear weapons.