Image copyright AP Image caption Mr Trump has been calling world leaders in recent weeks

US President Donald Trump has sent a letter to Xi Jinping, his first direct approach to the Chinese leader.

The president thanked Mr Xi for congratulating him on his inauguration last month and said he looked forward to "constructive" relations.

Mr Trump has not yet spoken to Mr Xi but did call other world leaders.

Chinese foreign ministry spokesman Lu Kang said his country attached great importance to the letter, Reuters news agency reports.

He commended Mr Trump for sending Lunar New Year greetings to the Chinese people and said co-operation between the two countries was the only option.

Change in tone

The letter, featuring standard diplomatic pleasantries, comes after a steady stream of belligerent attacks aimed at Chinese trade and policies.

In recent months, Mr Trump has challenged Beijing on sensitive issues such as Taiwan and the South China Sea. He angered China by taking a call from Taiwan's President Tsai Ing-wen, the first involving a US president or president-elect in decades.

China sees Taiwan as a breakaway province to be reunited with the mainland, by force if necessary. The US cut formal ties with Taiwan in 1979.

"President Trump stated that he looks forward to working with President Xi to develop a constructive relationship that benefits both the United States and China," the letter said, according to the White House.

Mr Trump also wished the Chinese people "a happy Lantern Festival and prosperous Year of the Rooster".

Lunar New Year celebrations officially end on Saturday with a Lantern Festival.

Image copyright EPA Image caption China has been angered by Mr Trump's comments on the One China policy concerning Taiwan

The conciliatory tone is in stark contrast to previous statements by Mr Trump, whose presidential campaign was marked by anti-China rhetoric that continued after winning the election.

In December, before his inauguration, Mr Trump posted a series of tweets criticising China for its exchange rate policy and its operations in the South China Sea.

He also questioned the One China policy, which is the diplomatic acknowledgement by the US of Beijing's position that there is only one Chinese government, following his call with Taiwan.

Shortly after he took office on 20 January, his administration vowed to prevent China from taking territory in the South China Sea.

Beijing has so far responded cautiously, expressing "serious concern" about Mr Trump's position on the One China policy, and urging the US to maintain close ties with China.

It also lodged a protest over the phone call with Ms Tsai, dismissing it as a "petty trick", and maintained it would "defend its rights" in the South China Sea.

But state media outlets have been less restrained and have issued strongly-worded rebukes, blasting Mr Trump for "playing with fire" on the Taiwan issue.

They also warned of serious action and a "resolute battle" against Mr Trump.