China has urged Iran to increase cooperation with the United Nations nuclear agency to resolve outstanding questions about Tehran's nuclear program.

A Chinese foreign ministry spokeswoman Jiang Yu also welcomed Iran's agreement last month with the International Atomic Energy Agency to answer questions about its past nuclear work within the next few months.

The spokeswoman made the comments after Iranian Interior Minister Mostafa Pur-Mohammadi arrived in Beijing Thursday for talks on the nuclear issue.

Israeli Foreign Minister Tzipi Livni said Thursday that the U.N. should impose tougher sanctions against Iran to try to stop its nuclear program.

But Iran's chief nuclear negotiator Ali Larijani said Wednesday that Tehran will not stop sensitive nuclear work.  Iran has also warned that more sanctions could jeopardize its cooperation with the U.N. nuclear agency.

In other developments, the United States says it will host a meeting of the five permanent U.N. Security Council members and Germany next week (September 21) in Washington to discuss the Iranian nuclear issue. 

The U.S. and its allies want the Security Council to impose a third set of sanctions on Iran for refusing to stop sensitive nuclear activities.

The United States and its allies allege Iran is trying to develop nuclear weapons under the cover of a civilian energy program, a charge Tehran denies.

Some information for this report was provided by AFP, AP and Reuters.