Chinese Premier Li Keqiang has sent a congratulatory message to Prime Minister Lee Hsien Loong on the occasion of Mr Lee assuming a new term.

"I would like to extend, on behalf of the Chinese government and in my own name, sincere congratulations and best wishes to you," Mr Li said in the letter released by the Chinese Embassy in Singapore on Monday.

"Under your outstanding leadership, Singapore has enjoyed sustained economic growth, increasingly improved its people's livelihood and made important contributions to peace, stability and prosperity of the region," Mr Li said.

Noting that China and Singapore are friendly and close neighbours, Mr Li said the Chinese government attaches great importance to the friendly and cooperative relationship with Singapore.

"Since the establishment of diplomatic ties 25 years ago, our practical cooperation has been substantially enhanced across the board and produced fruitful outcomes," he said.

"I am ready to closely work with you to promote the China-Singapore relationship to new heights," Mr Li added.