President Hassan Rouhani has emerged a winner from the Iran nuclear deal but if he is to cement his moderate reputation he must confront long-sidelined domestic political challenges, analysts said.

The nuclear talks dominated Rouhani's first two years in office, with previously unsignalled direct negotiations with the United States allowing him to begin to transform Iran's international relations.

But the sheer task of ending the nuclear dispute, and the opposition from hardliners against diplomacy back home, overwhelmed his reform-minded domestic policy agenda.

Ever since he spoke by telephone with US President Barack Obama in September 2013 -- a first since Iran's Islamic revolution in 1979 -- Rouhani has been characterised as a politician capable of change.

With the nuclear deal all but sealed Iranians are feeling a sense of relief but they have not forgotten other promises Rouhani made before his election, said Davoud Hermidas Bavand, a political analyst.

And it is on difficult domestic issues that the president, a moderate in a country with a strong conservative system, will ultimately be judged, according to Bavand, a lecturer at Tehran University.

"The agreement has created a sense of happiness, there is no doubt about that, but the follow-up is that there are big problems in our society," he said.

"I do believe Mr Rouhani now has a stronger hand but the problems are not just economic, but also include political prisoners."

- Past appeal, present challenges -

Before he was elected Rouhani said there was a need to tackle the prisoners issue, especially those jailed after the disputed re-election of president Mahmoud Ahmadinejad in 2009.

"I hope that within a year of this election a situation will come about that not only those under house arrest can be freed but also those in prison because of 2009," Rouhani said at a campaign event.

The comment came after Rouhani was asked by students what he would do about the house arrest of Mir Hossein Mousavi and Mehdi Karroubi, reformist presidential candidates who said the vote was fraudulent.

Rouhani's stance appealed to voters from a reformist movement crushed after 2009. Only recently, by the formation of two new political parties, have reformists began to re-emerge.

However Rouhani has not yet tackled the issue and some of his supporters, including members of his cabinet, have been accused of backing the sedition -- the regime's term for the street protests that erupted after the 2009 ballot in which dozens were killed.

Although the nuclear deal, which will lift sanctions and pave the way for a better economy, is an achievement Rouhani must push hard to bring about a more inclusionist political atmosphere, Bavand said.

"A new curtain has opened and Mr Rouhani must use this opportunity," he said.

"If he is going to be a man of history then he cannot just be bound to maintaining his own position. He has to take risks," he added.

- Ballot box test -

Parliamentary elections in February 2016 could be a turning point.

Since taking office Rouhani has encountered resistance from a heavily conservative legislature, including over the nuclear talks, and from the country's powerful clerical establishment.

But the public support and political momentum from the nuclear deal, only made possible because supreme leader Ayatollah Ali Khamenei backed it, is a chance for the president's allies to create conditions for voters to elect a more moderate parliament next year.

Saeed Laylaz, an economist and reform-leaning analyst, said rather than devoting his time to winning over reformists, Rouhani needs to exert his influence within the regime ahead of the poll.

Referring to Iran's Guardian Council, a powerful committee that vets and excludes candidates, Laylaz said: "The nuclear deal is a big win for Mr Rouhani and he can use it to create a coalition of reformists and those in the middle of the road. He will try to bargain with the council to accept more moderate candidates. That is his most important job."

Bringing job gains from the nuclear deal after years of a flattened economy and high unemployment will also occupy Rouhani, who faces a re-election battle in 2017.

"He now has to start thinking about his second round as president," Laylaz said.

The nuclear deal can though be presented as a mandate for domestic change, according to Amir Mohebbian a conservative analyst who believes Iran would benefit from reform.

"Mr Rouhani has made a paradigm shift. From the very beginning the main axis of his plans was about understanding and finding an agreement with the West on the nuclear programme," Mohebbian said.

"Now it seems he can say to Iranian society that I achieved my first plan successfully."