By Dan Griffiths
BBC News, Beijing
Iran's top nuclear negotiator Ali Larijani is on a two-day trip to China.
Dr Larijani will spend two days in China
His visit comes after the UN Security Council imposed restrictions on Iran's trade in nuclear materials and technology.
The restrictions are designed to pressure Tehran to halt work on its nuclear programme.
Mr Larijani is believed to be carrying a message from the Iranian leader, Mahmoud Ahmedinejad, for Chinese President Hu Jintao.
Mr Larijani will also meet other senior Chinese officials during his trip, but no further details about this visit have been made available.
China has always faced a delicate balancing act in its dealings with Iran.
Beijing needs Iranian oil and gas for its booming economy, and China supports Iran's right to a nuclear programme.
But as a permanent member of the UN Security Council, it backed last month's resolution imposing sanctions on Iran.