BRUSSELS - Leaders of China and the European Union on Tuesday called for strengthened cooperation in order to achieve mutually beneficial development.

Premier Wen Jiabao and European Council President Herman van Rompuy sent the message in their congratulatory letters kicking off the Sino-EU Forum organized by Brussels-based think tank Friends of Europe and the Mission of China to the EU.

"The international situation is undergoing profound and complicated changes, and the world is faced with many severe challenges," Wen was quoted as saying in his letter.

"As two key strategic forces in the world, China and the EU should continue to stand together in the face of difficulties, pursue mutually beneficial cooperation and expand their cooperation to achieve common development," said Wen.

In reading Van Rompuy's message, his principal adviser Zoltan Martinusz said strengthening the strategic partnership is the lasting personal commitment of the European Council president, who visited China in May.

Regarding China, Martinusz said: "The EU's strategic choice is not rivals or partners; the strategic choice is about what kind of partners we will be."

Hua Chunying, counselor at the European Department of the Foreign Ministry, said the two sides need to deepen their partnership with "confidence, tolerance and patience".

Apart from business and trade relations, Meng Xiangqing, deputy director of Strategic Research Institute at the National Defense University of the People's Liberation Army, said the most sensitive aspect of EU-China relations is military affairs.

Meng added that boosting defense and security exchanges between the two sides is still a challenge.

"I think the EU side should move faster in this regard to boost mutual trust politically," said Meng.

"This does not necessarily mean that China will import advanced weapons and equipment from the EU. This is a political signal, instead," said Meng.