MOSCOW, March 27 (Xinhua) -- Visiting Chinese President Hu Jintao and his Russian counterpart Vladimir Putin vowed Tuesday to expand cooperation in trade, economic, social and cultural fields.

The two leaders made the pledge at the opening ceremony of a four-day Chinese national exhibition in Russia Tuesday morning.

It is the largest overseas comprehensive exhibition by China in almost three decades and one of the around 200 events planned for the ongoing "Year of China" in Russia.

The two presidents visited the exhibition, which covers more than 20,000 square meters and showcases some 15,000 products from 30 industries such as energy, machinery, automobile and home appliances.

Hu called on the two countries to explore new fields for growth in trade and economy, enlarge its scale and improve efficiency, so as to push the China-Russia strategic partnership of cooperation to a new high.

Russia regarded China as "a major economic partner," Putin said, adding that the exhibition would help the Russians know the industrial and technological progress China has made in its reform and opening-up drive.

Putin hailed the growing Russia-China trade and economic ties, saying bilateral trade turnover has increased five-fold since 2000to more than 30 billion U.S. dollars.

China-Russia trade has witnessed rapid growth for eight consecutive years, reaching 33.4 billion U.S. dollars in 2006. It is expected to reach 60 billion to 80 billion U.S. dollars by 2010, according to official statistics.

Chinese enterprises were expected to sign four contracts worth over 500 million U.S. dollars to buy machinery and electrical products from Russia at the exhibition, as well as another six contracts to supply machinery and electrical products worth 1.128 billion U.S. dollars to Russia.

Official statistics show the China-Russia bilateral trade turnover of machinery and electrical products stood at 5.85 billion U.S. dollars last year, of which 247 million U.S. dollars was exports from Russia. Overall, Russia mainly delivered oil, petrochemicals and timber to China.