After years of debate and discussions between Iran and the major powers - Britain, China, France, Germany, Russia and the United States - an agreement on Tehran's nuclear program appears imminent.

In 17 days of talks in Vienna the negotiators have passed three deadlines. The latest, on Monday at midnight, expired without a statement.

Instead, representatives from the two sides were due to meet again at 10:00 local time (0800 UTC) on Tuesday for a comprehensive meeting.

In the early hours of Tuesday morning the group of the five permanent members of the United Nations Security Council plus Germany held a one-hour meeting.

Reporters at the scene suggested the discussion concerned UN access to all suspect Iranian sites, as the negotiators tried to complete the deal.

Almost all of the 100-page agreement has reportedly been settled. But discussion on an arms embargo has caused a delay.

Currently, there are six United Nations resolutions banning Iran from enriching uranium. Four of the resolutions also impose sanctions.

Two UN resolutions (#1747 from 2007 and #1929 from 2010) place an embargo on selling arms to Iran. They also ban the supply of parts and technology to Iran's ballistic missile program. Tehran wants all the restrictions removed.

In brief remarks to journalists on Monday, US Secretary of State John Kerry said he was "hopeful" and that the talks were "getting to some real decisions."

jm/cmk (Reuters, AFP)