LONDON (AFP) - Britain on Monday accused the new Iranian regime of failing to implement promised human-rights reforms, and warned there was little imminent hope of improvement.

The Foreign Office report said there were "serious" concerns over religious freedoms and the treatment of journalists, despite the thawing of international relations with Teheran following the election of Mr Hassan Rouhani last June.

"There was no substantive improvement in the human rights situation in Iran between October and December 2013," it said.

"The Iranian government continued to make positive public statements on civil rights issues, but there has been no sign of institutional change to improve the human rights situation, including for minority religious and ethnic groups, journalists and human rights defenders, prisoners and women."

It welcomed Mr Rouhani's release of a draft charter of citizens' rights in November, but stressed that "without changes to the law or the approach taken by the judiciary and security forces, there is unlikely to be any real change".

Iran halted production of 20 per cent enriched uranium on Monday, marking the entry into force of an landmark deal with world powers on its disputed nuclear programme.