China has welcomed US President Donald Trump's letter to President Xi Jinping, saying it "highly appreciated" Mr Trump's Chinese New Year greeting.

This, despite the letter arriving on President Xi's table three weeks after Mr Trump took office. During this time, the US President has had phone conversations with other world leaders, including Russian President Vladimir Putin and Japanese Prime Minister Shinzo Abe.

The White House said on Wednesday that Mr Trump had written to Mr Xi thanking him for his congratulatory note on the former's inauguration on Jan 20 and wishing the Chinese people a prosperous Year of the Rooster. China responded by saying it is willing to work with the superpower to promote cooperation.

But observers cautioned that Beijing should not interpret Mr Trump's letter as a gradual change in his hardline attitude towards China.

SEE WORLD: Trump's letter not sign of shift in stance: Analysts