officials close to the talks said on Thursday the deadline may be extended from Monday until March because of sharp disagreements between Tehran and world powers.

As six world powers and Iran race to meet a Monday deadline for resolving a 12-year-old dispute over Iran's nuclear program, officials close to the talks said on Thursday the deadline may be extended from Monday until March because of sharp disagreements between Tehran and world powers.

US officials allege the agreement “should slow the Iranian nuclear program enough that it would take Iran at least a year to make enough material for a nuclear bomb if it decided to ignore the accord.” “Our goal is to shut off each pathway sufficient that we know we have a breakout time of a minimum of a year,” Secretary of State John Kerry said last month.

This comes as a trilateral meeting between Iranian and US foreign ministers and the EU coordinator in Cobourg Hotel had ended after two hours of negotiations.

According to IRNA, John Kerry arrived in Vienna from Paris to join the Vienna 8 negotiations, which is supposed to be the last round of talks to lead to the signing of a comprehensive agreement by November 24.

The axis of Kerry-Zarif-Ashton talks will be deciding over the schedule of this round of negotiations as well as efforts made to resolve the remainder of disputes over Iran’s uranium enrichment and ways for lifting the anti-Iranian sanctions.

According to the US Department of State, Kerry had before these talks been engaged in bilateral and trilateral negotiations with the Iranian nuclear negotiation team to be informed about the latest stands of Tehran in Vienna 8.

Before his trip to Vienna, Kerry paid a visit to the French capital, Paris, where he met with foreign ministers of France and Saudi Arabia.

In a joint appearance before reporters, Kerry and Fabius expressed hope that progress could be made but acknowledged that some obstacles remained in the way of an accord. “We hope that the gaps that exist -- and they do exist -- can be closed,” Kerry said.

Sources close to the Iranian negotiating team say the main stumbling block in the way of resolving the Western dispute over Iran’s nuclear energy program remains to be the removal of all the bans imposed on the country, and not the number of centrifuges or the level of uranium enrichment.