Negotiators in Vienna, Austria, are set to make a final push to try to reach a deal on Iran's nuclear programme ahead of a midnight (23:00 GMT) deadline.

World powers - the US, UK, Russia, China, France and Germany - want Iran to curb its nuclear programme in return for the lifting of UN sanctions.

Tehran says it is not seeking nuclear weapons, but wants atomic energy.

"At the moment, we are focused on the last push... to try and get this across the line," British Foreign Secretary Philip Hammond said.

"Of course, if we're not able to do that, we will then look at where we're going from there."

A senior US state department official told reporters: "It is only natural that just over 24 hours from the deadline we are discussing a range of options... an extension is one of those options."

The delegates could also set out a framework of a deal that would be finalised later.

Iranian President Hassan Rouhani has said that "if the West does not make excessive demands, an agreement is within reach", according to Iran's Resalat newspaper.

Chinese Foreign Minister Wang Yi has arrived in Vienna, meaning the foreign ministers of all of the so-called P5+1 group are now in attendance.

He told reporters at the Palais Coburg hotel, where the talks are being held, that he had "come with a Chinese proposal for settling the various focal issues".

Source: BBC