Athens, Greece: Iran on Thursday warned global powers against making ‘excessive demands’ in talks aimed at sealing a ground-breaking nuclear deal, after France demanded access to its military installations.

‘I would expect my negotiating partners to refrain from making excessive demands,’ Iranian Foreign Minister Mohammad Javad Zarif said during a visit to Athens, adding: ‘People need to have their foot in reality, not in illusions.’

Zarif on Saturday is to meet US Secretary of State John Kerry in Geneva, after weeks of behind-the-scenes complex technical discussions in Vienna seeking to narrow the gaps on what would be an unprecedented deal on curtailing Iran's nuclear programme.

Iran and the six global powers leading the talks -- Britain, China, France, Germany, Russia and the United States -- laid down a framework to guide the final accord in eight days of marathon late-night talks in Lausanne in early April.

The negotiators are working towards a proposed 30 June deadline for agreement.

One of the major sticking points appears to be access to military sites amid lingering concerns about the possible military dimensions of the Islamic Republic's nuclear programme.

Tehran has always denied seeking to develop a nuclear bomb, saying its nuclear energy programme is for civilian purposes only.

But French Foreign Minister Laurent Fabius warned on Wednesday that France would oppose a final nuclear accord unless it allowed inspections of military sites.

Zarif on Thursday indicated that France's request amounted to a renegotiation of the Lausanne framework.

‘If people insist...on renegotiations, then it will be difficult to envisage an agreement,’ he said.

He said Iran wanted a ‘dignified, mutually respectful agreement.’