In a landmark move, US Secretary of State John Kerry will travel to Geneva Friday to join nuclear talks with US arch-foe Iran, fuelling hopes a historic deal may be in sight.

Kerry will go to the Swiss city "in an effort to help narrow differences in negotiations" and at the invitation of EU foreign policy chief Catherine Ashton, a senior State Department official said.

Upending an 11-day tour mostly of the Middle East, Kerry was due to arrive in Switzerland later Friday for the talks which had dragged for years until new Iranian President Hassan Rouhani came to power in August.

Iranian Foreign Minister Mohammad Javad Zarif and six world powers, known as the P5+1, are in the Swiss city aiming to broker a deal that could see Tehran freeze its disputed nuclear programme in exchange for relief from crippling sanctions.

Zarif said Thursday he believed it was possible to reach a deal with world powers by the end of the talks on Friday.

"I believe it is possible to reach an understanding or an agreement before we close these negotiations tomorrow evening," Zarif told CNN.

He said there had been agreement on a framework for the deal and that a joint statement could be drafted on Friday.

Kerry, who is in Amman, will first fly to Tel Aviv to meet with Israeli Prime Minister Benjamin Netanyhau and his surprise decision to go to Geneva is sure to infuriate key US ally Israel. Iranian leaders in the past have denied the Holocaust and threatened to destroy the Jewish state.

Any deal with the Islamic republic "would be "a mistake of historic proportions," Netanyahu said Thursday.

But officials have said a long-awaited agreement on curbing Iran's nuclear ambitions may be finally within reach, after years of fruitless talks.

In one of the highest level US-Iran contacts in years, Kerry met with Zarif at a P5+1 meeting at the United Nations in September, when US and international leaders said they were encouraged by the new approach by Rouhani, who is seen as a relative moderate.

US President Barack Obama also made a historic phone call to Rouhani.

Washington and Tehran have not had diplomatic relations for some three decades, following the 1979 Islamic revolution and the subsequent 444-day seige of the US embassy in the Iranian capital.

But the Obama administration has seized on overtures from Rouhani, hoping that there may be an opening to rein in Iran's suspect nuclear programme.

"We have always said that a diplomatic solution, through dialogue and diplomacy, to the Iranian nuclear file is something that not only we welcome but something that we support and appreciate," Kerry told reporters Thursday during his visit to Amman.

Obama said in an interview with NBC News Thursday that the agreement being fleshed out would keep the bulk of sanctions on the Islamic Republic in place, and any relief could be reversed.

"We don't have to trust them. What we have to do is to make sure that there is a good deal in place from the perspective of us verifying what they're doing," Obama said.

"There is the possibility of a phased agreement in which the first phase would be us, you know, halting any advances on their nuclear program, rolling some potential back, and putting in place ... some very modest relief, but keeping the sanctions architecture in place."

Western powers suspect Iran's uranium enrichment may be aimed at developing nuclear weapons, a claim Tehran denies.

And Zarif insisted to CNN: "There won't be a suspension of our enrichment in its entirety."

Iran's lead negotiator in Geneva, Deputy Foreign Minister Abbas Araqchi, had suggested Thursday that a major hurdle had already been crossed.

"The other side accepted Iran's proposed framework, the first step, the last step and the steps in between, and now we have to discuss the details of these steps," Araqchi said in comments shown on Iranian state television.

In a further sign that the talks may be making progress, Zarif cancelled a planned trip to Rome.

Both sides have said the recent talks have been the most productive in years but admit reaching a deal will not be easy.