President Barack Obama has admitted exchanging letters with the Iranian president, Hassan Rouhani, in a move which could set the stage for the first meeting between a U.S. and Iranian leader since Iran’s 1979 revolution.

It is hoped a meeting could lead to a solution in the row over Iran’s nuclear weapons programme, which Obama said is ‘larger than the Syrian crises’ .

Foreign secretary William Hague is also said to be due to meet Mohammad Javad Zarif, Iran’s minister of foreign affairs, at the UN general assembly meeting in New York.

But Obama admitted that it would not be easy.

In a television interview aired on ABC News, on Sunday, when asked whether he and Rouhani had ‘reached out’ to each other, Obama confirmed that they had exchanged letters, the Guardian reports.

Obama said: ‘I have. And he’s reached out to me. We haven’t spoken directly…’

He added: ‘Negotiations with the Iranians is always difficult.

‘I think this new president is not going to suddenly make it easy.’

Tehran has reportedly also tweeted on President Rouhani’s Twitter account that he would also meet Hague, despite the UK not requesting a meeting.

The Foreign Office said it had not had official word from Tehran about a meeting.

The US and its allies suspect Iran of seeking a nuclear weapons capability.

Tehran says its nuclear programme is purely for peaceful purposes, but Israel regards it as a threat to its existence and refuses to rule out military action.

With the election of an apparently more pragmatic president in the Glasgow educated moderate Rouhani, it has been hoped Western countries might see a better chance for diplomacy and strike a deal to curb Iran’s uranium enrichment programme and avoid any conflict.

The tweet has been accepted with cautious optimism.

If Mr Hague meets with Rouhani or Zarif it could heal the diplomatic wounds which were opened when the British Embassy in Tehran was attacked by a mob in 2011.

The last meeting between an American and Iranian leader was in 1977 when President Carter met Shah Mohammad Reza Pahlavi.

During the interview Obama suggested involving Iran in wider talks on Syria.

He said Tehran needed to recognise the impact of what was happening in Syria, adding:  ‘… what’s happening there is a train wreck that hurts not just Syrians but is destabilising the entire region.’

Obama said that Iran’s leaders should not take comfort in the fact that America has not used force against Syria and remember that preventing a nuclear arms race in the Middle East was a higher priority for the U.S than than ridding Syria of chemical weapons.

‘On the other hand, what they should draw from this lesson is that there is the potential of resolving these issues diplomatically.’