Chinese President Xi Jinping (L) holds talks with Serbian President Tomislav Nikolic in Belgrade, Serbia, June 18, 2016. (Xinhua/Li Tao)

China and Serbia upgraded their bilateral relationship to Comprehensive Strategic Partnership on Saturday after close talks between the two presidents, with more than 20 cooperative documents signed.

Serbia has become the first country in the Central and East Europe (CEE) region to establish a Comprehensive Strategic Partnership with China after visiting President Xi Jinping and Serbian President Tomislav Nikolic signed a joint declaration.

Witnessed by the two presidents, more than 20 cooperative documents covering areas including economy and trade, production capacity, and finance, also were signed on Saturday morning. China and Serbia are "all-weather friends" and have a "special brotherly bond", and both sides should expand their ties, Xi said after signing the joint declaration.

The two countries will enhance cooperation in key areas including infrastructure, industry and agriculture, Xi said, adding that China-proposed Belt and Road Initiatives have been supported by Serbia.

China and Serbia should uphold the principle of mutual respect, treating each other equally, and cooperate to achieve win-win results, Xi said, adding that the two sides should understand each other's core interests and major concerns.

Nikolic called for more cooperation with China to deepen the bilateral friendship made by several generations of leaders. He invited Chinese companies to invest more in Serbia.

Noting that China has never invaded other countries in its history, Nikolic said that China is a great nation that loves peace and dislikes conflicts.

"The whole world should thank the Chinese government and people for the contributions they made to world peace," he said.

After the signing ceremony, Xi received the Order of the Republic of Serbia on a Grand Collar, the country's top award, from Serbian President Tomislav Nikolic. The medal has been granted only once — to Russian President Vladimir Putin in 2014 — after its launch in 2009.

During the visit, Xi received a rare high-level reception, with a welcome ceremony attended by both President Nikolic and Prime Minister Aleksandar Vucic, at the airport upon his arrival.

Soon after his arrival on Friday, Xi paid homage to the Chinese martyrs killed in the NATO bombing of the former Chinese Embassy in the Federal Republic of Yugoslavia in May 1999.

Chu Yin, a researcher at the Beijing-based University of International Relations, said that China-Serbia cooperation should be seen as an example for developing ties with Central and East European countries.

There is great potential for the development of bilateral economic ties, given the fact that the current Chinese investment in Serbia remains less than many countries in the EU, he said.

Denis Depoux, Asia deputy president of the Munich-based consulting firm Roland Berger, said that Serbia has a long tradition in manufacturing industrial goods, but it has long been neglected by investors due to political reasons.

"Serbia is one of the hot spots of investment in Europe at the moment," he said, adding that the geographic location of Serbia, connecting the east and west of Europe, has made it an ideal place for China's initiatives to revive the ancient Silk Road.