TEHRAN - Iran and China on Friday celebrated here the 40th anniversary of the establishment of their diplomatic relations, as a Chinese leader visited to strengthen political and economic ties.

He Guoqiang, a senior official of the Communist Party of China (CPC) currently on a three-day official visit, and Iranian Vice President Mohammad-Javad Mohammadizadeh attended a reception held by the Chinese Embassy to mark the occasion.

"On behalf of the Chinese government and people, I warmly congratulate the 40th anniversary of the establishment of diplomatic relations between China and Iran, and convey sincere greetings and best wishes to Iranian people," He said at the ceremony.

He added that both China and Iran were countries of ancient civilizations and enjoyed historic relations, saying that since 2,000 years ago, the ancient Silk Road has connected two countries together, and the friendship between two countries has withstood the hardship of time and history.

The establishment of diplomatic relations on August 16, 1971 opened a new chapter for the expansion of bilateral relations between China and Iran, He stressed.

Although the international and regional situation changed dramatically during the past 40 years, bilateral relations between the two countries have maintained a good momentum. Especially in recent years, high-level contacts between two countries have been deepened and political mutual trust has been enhanced, He said.

In 2010, bilateral trade reached a record of some $30 billion, which means thousands of times in comparison to the earlier years of establishing relations. In the past year, Iran has become China's second trade partner and was one of the major providers of energy to China, He said.

He said China spoke highly of the traditional friendship between the two sides in recent years. Noting that the international and regional situations are undergoing profound and complicated changes, He stressed that the two countries are faced with great development opportunities and challenges.

Based on the principles of mutual trust, mutual benefit and common development, China is willing to work with Iran to intensify mutual exchange and collaboration and enhance bilateral friendly relations between two countries to a new level, He said.

He, a member of the Standing Committee of the Political Bureau of the CPC Central Committee and Secretary of the CPC's Central Commission for Discipline Inspection, is the second senior CPC official to visit Iran in less than a year.

Li Changchun, also a member of the Standing Committee, paid a visit to Iran last September.

The visits underlined the close political and economic relations between China and Iran, which has been engaged in bitter diplomatic clashes with the United States and some other Western countries over its nuclear program.

The West has alleged that Iran has been pursuing a covert nuclear weapon project and slapped harsh sanctions on the country, but Tehran has repeatedly said its nuclear endeavor is solely for peaceful purpose.

China, while respecting the sanctions imposed by the United Nations Security Council against Iran, opposes some of the harsher punishments taken by Western countries and has maintained business and trade relations with Iran. China also calls for a peaceful solution to the Iran nuclear issue through dialogue and negotiation.

Iranian Vice President Mohammad-Javad Mohammadizadeh said at the ceremony that during the past years, Iran and China witnessed the significant growth of the relations in political, economical and cultural areas.

He further pointed out that Iran and China, as two friends, played key roles in establishing world and regional peace and stability, hoping that He's trip to Iran would pave the ground for the further cooperation between the two countries.

He travelled to the Iranian capital Tehran on Friday afternoon, where he will meet with top Iranian leaders on Saturday, including President Mahmoud Ahmadinejad and Parliament speaker Ali Larijani.

He will also witness the signing of government and business agreements that worth over $4 billion on Saturday.

Iran is the last leg of He's five-nation overseas trip which has already taken him to France, Poland, Serbia and the United Arab Emirates. He also made a stopover in Turkey after visiting Poland. He will leave Tehran for Beijing on Saturday afternoon.