Cui Tiankai, assistant to Chinese Foreign Minister, will visit Iran and Russia from April 14 to 18, Chinese Foreign Ministry spokesman Liu Jianchao said in Beijing yesterday.

"Cui will exchange views with Iranian and Russian diplomats on Iranian nuclear issue and other issues of common concern," Liu told a regular news conference.

Iranian President Mahmoud Ahmadinejad announced on Tuesday that Iran had successfully produced low-grade enriched uranium and was at the threshold of global nuclear club.

"The visit of Cui aims at stepping up exchanges with all parties concerned in a bid to help resolve the Iranian nuclear issue properly," Liu said.

International Atomic Energy Agency (IAEA) Director-General Mohammed ElBaradei started his visit to Iran Thursday morning upon an invitation extended by chief of Iran's Atomic Energy Organization Gholam-Reza Aqazadeh.

ElBaradei will meet with senior Iranian officials and hold consultations with them on the continuation of Iran's constructive interaction and cooperation with the UN nuclear watchdog.

"China is concerned about the statement by the Iranian side and is worried about the way in which things are developing," Liu said.

China appeals to relevant parties to show restraint and not take actions that might aggravate the situation, he said, adding the issue should be properly settled through negotiations and diplomatic efforts.

Military and other sanctions will not be helpful in the current Iranian situation, and diplomatic solution is the best way out, analysts say.