New President Hassan Rowhani's experience as Iran's nuclear negotiator will go a long way toward changing the "tone" of talks with major powers and could lead to an easing of sanctions, analysts say.

His negotiating skills won him the respect of his European interlocutors and the monicker "diplomat sheikh".

But his policies under reformist president Mohammad Khatami were abandoned in 2005 when President Mahmoud Ahmadinejad was elected and Rowhani quit his post over differences.

"Rowhani cannot change the core of Iran's nuclear strategy, which is determined by the supreme leader," Ayatollah Ali Khamenei, Ali Vaez, the Brussels-based International Crisis Group's senior analyst on Iran, told AFP.

"But what he can alter is the tone and the team," while easing Tehran's isolation, he said.

"Adopting a more conciliatory rhetoric and engaging more experienced negotiators could have a positive impact on nuclear negotiations with the P5+1," UN Security Council permanent members, Britain, China, France, Russia, the US, plus Germany.

Afshon Ostovar, a Middle East and Iran analyst in the US-based CNA research centre, also believes that Rowhani's success would depend on Khamenei.

"Above all, what Rowhani is able to accomplish will depend on how much support he receives from Khamenei," he said.

Rowhani is a representative of Khamenei on the Supreme National Security Council, Iran's top security body, and was its secretary for 16 years until 2005, and has played up his ties with Khamenei.

Tehran has been engaged since 2006 with the P5+1 over its controversial nuclear work, but with no breakthrough. It has as a result come under mounting international sanctions and isolation.

In his first statement after his win was confirmed, the moderate conservative cleric urged world powers to treat Iran with respect and recognise its rights, an apparent allusion to its nuclear policy.

"A new opportunity has been created by this great epic, and the nations who tout democracy and open dialogue should speak to the Iranian people with respect and recognise the rights of the Islamic republic," he said.

Mohammad Saleh Sedghian, head of the Tehran-based Arabic Centre for Iranian Studies, believes the seasoned diplomat is the man to engage in talks with Iran's archfoe, Washington, to find a solution to the nuclear issue.

"In one of his campaign speeches, Mr Rowhani said that since the majority in the 5+1 are under pressure from the US, Iran should negotiate with the side that exerts it, Washington," he pointed out.

"So he will talk directly to the US to solve the issue" Sedghian told AFP.

Following Rowhani's victory, the United States itself said it was prepared to engage Iran directly over its nuclear programme, which the West suspects is aimed at building a bomb, despite Tehran's constant denials.

Such engagement would be aimed at reaching a "diplomatic solution that will fully address the international community's concerns about Iran's nuclear programme," said the White House.

However, "Rowhani is the ultimate regime insider, who knows how to build bridges. I think it would be unlikely and unwise for him to alienate powerful stakeholders such as the IRGC (Islamic Revolution Guards Corps) or the conservatives," said Vaez.

The elite force has been a major stakeholder in many of the country's macro projects, especially transportation, construction and the import-export business, according to government data.

Many of its members have stepped out of uniform and launched political careers.

Mohammad Baqer Qalibaf and Mohsen Rezai who lost Friday's presidential election were both decorated top commanders of the Guards.

Domestically, Rowhani, who was boosted by the backing of Khatami and former pragmatic president Akbar Hashemi Rafsanjani and was able to fend off hardline conservatives, does not fear the wrath of the conservative camp, Sedghian said.

"Since these names in the conservative camp lost to Rowhani, they are not going to make problems on his path to setting up a cabinet," he said.

Ostovar said the delicate balancing act between domestic forces would pose a challenge for Rowhani but that the new man in Iran's highest elected office should be given time.

"I would not expect him to put forward any bold initiatives that could face resistance from his opponents, at least not in the short term," he said.

And whereas Ahmadinejad stirred international outrage with his outspoken anti-Israeli rhetoric and doubts over the Holocaust, Iran's image around the world under Rowhani will change, said an Iranian analyst.

His predecessor was "the face of Iran in the world. This image will now change. From now on, it be that of a level-headed, calm ... man with a moderate tone," he told AFP, asking not to be named.