China's Warning On Deadlocked Iran Talks

China has called for both sides to compromise in nuclear talks between Iran and world powers, warning that all previous efforts will be wasted if a deadlock continues.

The talks in Lausanne, Switzerland, will drag on into Thursday, the State Department said, a day after negotiators agreed to a one-day extension .

After Chinese foreign minister Wang Yi left the meeting, a rare statement from his delegation said: "It is important to give political guidance to the negotiations ... it is important to narrow down the differences.

"If the negotiations are stuck, all previous efforts will be wasted.

"All parties must be prepared to meet each other half way to reach an agreement."

Mr Wang was one of three foreign ministers to leave the negotiations in the hands of representatives, with Russia's foreign minister Sergei Lavrov and France's Laurent Fabius also departing.

The significance of their absence was not clear.

Iran's foreign minister said earlier he was hopeful Tehran and the six world powers - the US, Britain, France, Germany, Russia and China - could begin drafting a preliminary deal after the negotiations were extended.

Mohammad Javad Zarif described the late-night talks as "very good", saying: "We hope to start drafting the text on Wednesday."

Britain's Foreign Secretary Philip Hammond said: "We have made some very significant progress over the last few days, but it has been slow going.

"We decided to break last night. Some of the staff had been working through the previous night. We wanted people to be fresh as we started the last few issues that remain.

"We are now working on them this morning. I'm optimistic that we will make further progress this morning, but it does mean the Iranians being willing to meet us where there are issues that we still need to deal with.

"So fingers crossed and we hope to get there during the course of the day."

Western powers aim to stop Iran from having the capacity to develop a nuclear bomb, in exchange for easing international sanctions that are crippling its economy.

Stumbling blocks related to Iran's enrichment research and the speed of lifting the sanctions are threatening to scupper an agreement.

The aim is to reach an understanding that could serve as the basis for a final accord to be reached by the end of June.

The talks, which have lasted nearly two years, have already been extended twice since an interim agreement was reached in November 2013 .

Israeli Prime Minister Benjamin Netanyahu, who opposes the negotiations, said the agreement being put together in Lausanne sends the message "that Iran stands to gain by its aggression".