Iran on Saturday announced dates for a three-day oil and gas conference in London in February designed to attract foreign investors awaiting new contract terms to be unveiled next month.

Oil majors have expressed interest in returning to Iran as soon as international sanctions linked to its nuclear programme are lifted, but they are currently still barred from signing any deals.

A nuclear agreement between Iran and world powers, struck in July, is due to be implemented in December or January and a top official said the timing had influenced the London event.

The "Iran Oil and Gas Summit Post Sanctions" event in Britain's capital is scheduled for February 22-24, said Seyed Mehdi Hosseini, head of the country's oil contracts re-negotiation team.

"It is predicted sanctions relief will start from January 2016, so the London conference date is in February," Hosseini told SHANA, the oil ministry's news service.

Iran has said it will publish the terms of post-sanctions oil contracts at a November 21-22 conference in Tehran, where 50 new oil exploration and production projects will also be announced.

"After the official lifting of sanctions in January, foreign companies and investors can attend this conference without any international restrictions," Hosseini said of the London event.

An announcement about the new contracts has been postponed several times because of Iran's long-running talks about its nuclear programme with six top powers led by the United States.

But following the July 14 accord struck in Vienna between Tehran and world powers, Iran wants to increase its share of the global energy market, which was badly hit by sanctions.

Under the nuclear deal with Britain, China, France, Germany, Russia, and the US, Iran agreed to limit its atomic activities in exchange for the lifting of all nuclear-related sanctions.