With only two days before a deadline for a deal on its nuclear programme, Iran's foreign minister is returning to Tehran from talks in Vienna for consultations.

According to Iranian media, Mohammed Zarif's return to the Iranian capital was planned in advance.

Zarif is likely to receive instructions on issues where the two sided remain apart - among them the extent of access Tehran should allow UN nuclear experts monitoring Iran's compliance to any deal.

All parties at the negotiating table insisted that Tuesday remains the formal deadline for a deal. But with time running out, officials conceded there could be slippage.

Iran nuclear talks at crucial stage

Federica Mogherini, the European Union's top diplomat, said: "If a few days more are needed, we will take them".

After being asked about the chances of a deal, she said: "it is going to be tough ... but not impossible."

Al Jazeera's James Bays, reporting from Vienna, said that although the minister's leave was not pre-announced, US officials appeared relaxed about it.

"It seems like everyone is accepting that the deadline might be extended, with the Iranian foreign minister returning to Tehran," he said.

"Altough officials talk about a few days, not more."

The negotiations between Iran and six major powers in Vienna are centred on a deal that would control Iran's capacity to make nuclear weapons in exchange for sanctions relief.

Tehran insists it does not want such arms and that its programme is purely for peaceful purposes.

Source: Al Jazeera And AP