Iran-World powers are struggling to reach an interim deal with Iran to limit its nuclear programme, as talks in Geneva move into a second day.

The Geneva talks, which are scheduled to conclude on Friday, involve Iran and representatives of the so-called P5 1 - the US, UK, France, China and Russia, plus Germany.

Reports suggest the talks could run into the weekend, and US Secretary of State John Kerry may join in later.

EU foreign policy chief Baroness Catherine Ashton is leading the talks for the world powers.

She has begun a meeting with Iranian Foreign Minister Mohammed Javad Zarif.

On Thursday, Iranian Deputy Foreign Minister Abbas Araqchi was quoted by the Mehr news agency as saying the first day of talks had been "useful" but that "serious issues remain a source of difference".

However, US politicians have indicated they will push forward with a bill proposing more sanctions against Iran next month if the talks fail.

Iran insists its nuclear programme is for peaceful purposes, but some world powers suspect it is seeking a nuclear weapons capability.