Chinese Foreign Ministry Spokesman Hong Lei said Saturday the Geneva international talks on the Iranian nuclear issue have reached the final moment.

Hong said in a press release that Chinese Foreign Minister Wang Yi left Beijing for Geneva early Saturday morning to participate in the dialogue between Iran and 5+1 nations, namely China, the United States, Russia, Britain, France and Germany.

The talks between Iran and the United Nations Security Council's five permanent members plus Germany over its controversial nuclear program have extend into an unscheduled fourth day on Saturday.

According to reports, U.S. Secretary of State John Kerry had flown to Geneva Friday to join the ongoing nuclear talks. Russian Foreign Minister Sergei Lavrov arrived in the Swiss city earlier Friday.

The new round of talks starting from Wednesday is the third negotiations between Iran and the six countries in more than a month.

The last around of talks held in Geneva from Nov. 7 to 9 failed to nail down an interim deal as expected.