The top foreign diplomats of the group known as the P5+1 will meet in Geneva Saturday amid reports that a deal with Iran on its nuclear program may be close.
China's Foreign Minister Way Yi left Beijing early Saturday for the meeting. Chinese officials say talks have reached a "final phase."
U.S. State Department Spokeswoman Jen Psaki says in light of the progress being made, Secretary of State John Kerry decided to go to Geneva with the hope that an agreement will be reached.
The foreign ministers from Britain, France, Russia and Germany will also be involved with the intense discussions with Iran.
European Union foreign policy chief Catherine Ashton has been leading the negotiations with the Iranians. The main sticking points have been to what extent Iran will be allowed to enrich uranium and how much sanctions would be eased.
Iran insists it keeps the right to enrich uranium and denies it wants to build a nuclear weapon. It has offered to suspend parts of its nuclear program and agreed to tighter inspections if the West relaxes sanctions that have devastated its economy.
Under discussion is a first-phase agreement meant to build trust while the two sides work out a more comprehensive deal that would ease Western concerns about Iran's ability to build nuclear weapons.
Iran's news agency IRNA on Friday called the talks "complicated and tough."
So far, the U.S. has said it is prepared to offer what it calls limited and reversible sanctions relief, including unfreezing billions of dollars in Iranian funds overseas. Iran has said it would also like restrictions eased on its oil exports and banking sector.
Former White House official and arms control specialist Gary Samore told VOA's Persian News Network Friday that resolving the nuclear issue is just one part of improving the relationship between the U.S. and Iran. He said the two nations continue to have disagreements on other issues, including Syria and the Israeli-Palestinian conflict.
"I think we have to recognize that resolution of the nuclear issue won't solve all of the issues that divide the U.S. and Iran, but resolution of the nuclear issue will make it easier to deal with those other areas of disagreement."
U.S. lawmakers, meanwhile, are threatening to increase sanctions if a deal is not reached. U.S. Senate Majority Leader Harry Reid said Thursday he is committed to moving forward in December with a bill to impose new measures on Iran if negotiations are not successful.
Reid said the bill would "broaden the scope of current petroleum sanctions, place limitations on trade with strategic sectors of the Iranian economy that support its nuclear ambitions, as well as pursue those who divert goods to Iran."
President Barack Obama and Secretary of State Kerry have been asking key Congressional leaders to hold off on any new sanctions against Tehran while the Geneva talks continue.
This is the third round of negotiations between Iran and the P5+1 group.
The latest talks began Wednesday, building on a prior round of negotiations that ended two weeks ago. Analysts say those talks failed in large part because of objections by France.