Chinese Foreign Minister Wang Yi(C) attends the plenary session on Iran's potential nuclear framework deal in Lausanne, Switzerland, on March 29, 2015. Foreign ministers from major world powers on Sunday night kicked off a plenary session to further bridge gaps on Iran's potential nuclear framework deal. [Photo/Xinhua]

For many western officials, since the opacity of Iran's nuclear program still remained contentious, Iran's full cooperation with the International Atomic Energy Agency (IAEA) is thus seen as an imperative if talks are to lead to a mutual understanding.

According to the source, much of the obstacles that prevented past negotiations from reaching their objective to find a viable point-by-point compromise have been removed, so the chance this time is really good to reach a framework achievement.

An anonymous negotiator told Xinhua that if the major things go well, the most possible time to "announce something" is the coming Monday.

However, whether the understanding will be a concrete document or a joint statement remained unknown.

On Nov 24 of 2013, the P5+1 (the United States, Russia, China, France, Britain, plus Germany) and Iran reached a first-step agreement on Iran's nuclear program, the Geneva 2013 Joint Plan of Action, which demanded Iran suspend some sensitive nuclear activities in exchange of limited sanction relief to buy time for the diplomatic effort to resolve the issue.

Since then, the P5+1 and Iran have twice missed self-imposed deadlines for a final and comprehensive accord, respectively in June and November last year, and the negotiators then set March 31 of 2015 as a new deadline for a political framework agreement and June 30 for the final deal.

From the beginning of 2015, the six major world countries have been negotiating with Iran almost nonstop, round after round and meeting after meeting, in an effort to put Iran's nuclear program under international control in return for easing of sanctions.