John Kerry
U.S. Secretary of State John Kerry addresses the 28th Session of the Human Rights Council at the United Nations in Geneva March 2, 2015. Reuters/Denis Balibouse

(Reuters) - The United States and France sought on Saturday to play down any disagreements over nuclear talks with Iran, saying they both agreed the accord now under discussion needed to be strengthened.

"We are on the same page," U.S. Secretary of State John Kerry told reporters after talks with French Foreign Minister Laurent Fabius in Paris.

"If we didn’t think that there was further to go, as Laurent said, we’d have had an agreement already," Kerry added. "The reason we don’t have an agreement is, we believe there are gaps that have to be closed. There are things that have to be done to further strengthen this. We know this."

The aim of the negotiations is to persuade Iran to restrain its nuclear program in exchange for relief from sanctions that have crippled its economy. Iran, a major oil exporter, wants the sanctions scrapped swiftly, the powers only in phases.

France's Fabius said on Friday commitments offered by Iran in the nuclear talks with six world powers do not go far enough and more work needs to be done, notably on what he called "volume, checks and duration".

On Saturday, Fabius made clear that by volume he meant the number and quality of centrifuges Iran might be allowed to operate under any deal. By checks, he meant an inspection and verification regime to ensure Iran does not violate the deal.

"There is still work to be done," said Fabius, whose government has positioned itself as more demanding on the conditions Iran must meet under any nuclear agreement.

As well as the United States and France, the other world powers involved in the Iran negotiations are Britain, China, Germany and Russia.

Western powers and Israel suspect Iran of having used its civil nuclear program as a cover to develop a nuclear weapons capability. Iran denies this, saying its nuclear program is solely for peaceful purposes such as generating electricity.

(Reporting By Arshad Mohammed and John Irish; Editing by Gareth Jones)