GENEVA (REUTERS) - US Secretary of State John Kerry said on Sunday that world powers had moved closer towards a deal during negotiations with Iran on reining in Teheran's nuclear programme and that "with good work" the goal could be reached.

Mr Kerry made the statement at a news conference after a three-day meeting between Iran and the six powers - the United States, France, Germany, Russia, China and Britain - that ended without an agreement.

Both sides, however, said progress had been made and negotiators would meet again on Nov 20.

Mr Kerry said differences had been narrowed during the talks in Geneva, which were aimed at securing an agreement that would curb parts of Iran's atomic activities in exchange for limited sanctions relief.

"Over the last two days a significant amount of progress was made," Mr Kerry said.

"There is no question in my mind that we are closer now as we leave Geneva than we were when we came, and that with good work and good faith over the course of the next weeks we can in fact secure our goal," he said.

But he also cautioned that the window for diplomacy "does not stay open indefinitely". Both the United States and Israel have refused to rule out possible military action against Iran if diplomacy fails to resolve the decade-old nuclear dispute.

Iran rejects Western accusations that it is seeking the capability to develop nuclear weapons.