By Prak Chan Thul
PHNOM PENH (Reuters) - U.S. President Donald Trump has written to Cambodian Prime Minister Hun Sen urging him to put the Southeast Asian nation back on a democratic path and seeking to improve ties with one of China's closest regional allies.
Hun Sen, who has ruled Cambodia for more than 34 years, has been under increasing western pressure to improve his human rights record, with the European Union threatening the withdrawal of important trade benefits.
The relationship with the United States has been particularly dire after Cambodian accusations of U.S. plotting against Hun Sen.
"It is important for the future of our bilateral relationship that you put Cambodia back on the path of democratic governance," Trump wrote in the letter dated Nov. 1 and seen by Reuters on Friday.
Critics have called Cambodia a one-party state since the Supreme Court dissolved opposition Cambodian National Rescue Party (CNRP) in 2017, paving the way for Hun Sen's ruling party to win all the seats in parliament in an election last year.
Hun Sen has accused the United States of supporting the CNRP and plotting a "colour revolution", like those that toppled eastern European strongmen, to overthrow his government.
Trump's letter said the strains in the relationship were bad for both countries.
"I wish to take this opportunity to underscore to you that the United States respects the sovereign will of the Cambodian people and we do not seek regime change," it said.
Still, it urged Hun Sen to "re-evaluate certain decisions taken by your government" that it said risks Cambodia's future stability.
The letter made no specific reference to China, but the United States has also voiced concern at growing military ties with Beijing.
On Nov. 9, Cambodia ordered the release from house arrest of opposition leader Kem Sokha, who was charged with treason two years ago. The charges remain and Kem Sokha is still banned from politics and from leaving the country.
In a Facebook post, Hun Sen said that he had received two letters from U.S. Ambassador Patrick Murphy on Thursday, which included an invitation letter for him to attend a special U.S. - ASEAN Summit in the U.S.
Government spokesman Phay Siphan said on Friday that the government agreed with the Trump's position in the letter.
"The Royal Government is making all efforts to give a high value to human rights and democracy," Phay Siphan told Reuters.
(Reporting by Prak Chan Thul, Editing by Kay Johnson, Matthew Tostevin and Jane Wardell)