President Xi Jinping and Russian President Vladimir Putin have each sent a congratulatory letter to the 10th China-Russia Expo ahead of the Russian leader's upcoming state visit to China.

The expo opened on Sunday in Harbin, the capital city of Heilongjiang province in Northeast China.

In his message, Xi noted that this year marks the 30th anniversary of the China-Russia strategic partnership of coordination and the 25th anniversary of the signing of the China-Russia Treaty of Good-Neighborliness and Friendly Cooperation.

Bilateral cooperation in various fields has been continuously deepened and solidified, achieving fruitful results thanks to the joint efforts of the two countries, Xi said.

It is hoped that the expo will serve as an opportunity for various sectors of the two countries to leverage their geographical proximity and complementary advantages, deepen all-round practical cooperation, further promote economic and social development, and continuously enhance the well-being of the two peoples, he said in the letter.

The goal is to make contributions to the steady and long-term development of the China-Russia comprehensive strategic partnership of coordination for a new era, Xi said.

Putin said in his message that the expo has evolved into the largest exhibition event between the two countries, providing a platform for direct and in-depth dialogue between the two sides.

It is believed that this expo will achieve positive results, plan for new prospects of mutually beneficial cooperation between the two countries and bring benefits to the two peoples, Putin said.

Last year, bilateral trade totaled $227.9 billion. In the first four months of this year, bilateral trade reached $85.2 billion, a year-on-year increase of 19.7 percent, according to the Chinese Foreign Ministry.

Aleksandr Sergeevich Kalashnikov, deputy mayor of Blagoveshchensk, said the expo has seen the number of exhibitors grow year by year, while the lineup of sectors involved continues to expand and diversify, and there are a growing number of agreements in the areas of high technology, joint production and green energy.

"In the economic sphere, we look forward to an increase in cross-border trade and the creation of new logistics chains. In terms of cultural exchanges, we look forward to expanding student exchanges and joint cultural festivals to strengthen the friendship between our two peoples," he said.

On Saturday, the Chinese Foreign Ministry announced that Putin will pay a two-day state visit to China starting from Tuesday.

Observers have expressed the hope that the visit will enhance bilateral coordination and mutual trust, help inject more certainty and positivity to the world's peace and security, and offer a greater boost to global prosperity and growth.