Chinese Premier Li Keqiang (R) meets with Federica Mogherini, European Union (EU) High Representative for Foreign Affairs and Security Policy and Vice President of the European Commission, in Beijing, capital of China, May 6, 2015. (Xinhua/Ding Lin)

BRUSSELS, May 6 -- European Council President Donald Tusk expressed his expectation on Wednesday that the European Union and China would raise the comprehensive strategic partnership between the two to a new level.

Tusk made the remarks in a letter to Chinese President Xi Jinping, as May 6 of this year marks the 40th anniversary of the establishment of diplomatic ties between China and the EU.

"The last four decades were truly successful in developing EU-China relations, promoting peace, prosperity and closer contacts between our societies," he said in the letter, which was released on Wednesday.

Tusk said the EU was committed to working constructively together to advance the causes of peace, security, prosperity, rule of law, social justice, green development and human rights.

"We are confident that the implementation of the EU-China 2020 Strategic Agenda for Cooperation will strengthen EU-China exchanges for the benefit of all," he said.

"I thank you for your invitation and I am looking forward to my next visit to China," he said.

On the same day, the European Council also released a letter from Tusk to Chinese Premier Li Keqiang on the celebration of the40th anniversary of diplomatic ties.

Tusk said he was looking forward to meeting Li at the 17th EU-China Summit this year because it would provide the opportunity to further advance the implementation of the EU-China 2020 Strategic Agenda for Cooperation.

Trade relations between China and the EU witnessed tremendous expansion from 2.12 billion euros (about 2.4 billion U.S. dollars) in 1975 to 543 billion euros in 2014, a remarkable 250-fold increase.