PHNOM PENH (Reuters) - Cambodian Prime Minister Hun Sen won words of support from China on Monday after the United States and European Union condemned the arrest of his main rival and a widening crackdown on his critics before next year’s election.

FILE PHOTO: Cambodia's Prime Minister Hun Sen, who is also president of the ruling Cambodian People's Party (CPP), arrives before a ceremony to mark the 66th anniversary of the establishment of the party, at Koh Pich island in Phnom Penh, Cambodia, June 28, 2017. REUTERS/Samrang Pring

A day after Kem Sokha was arrested in a midnight raid on his house, one of his deputies said donor countries should open their eyes to Cambodia’s “false democracy” and put more pressure on Hun Sen.

When asked about Kem Sokha’s arrest at a press briefing in Beijing, Chinese foreign ministry spokesman Geng Shuang said China “supports the Cambodian government’s efforts to protect national security and stability.”

Opposition politicians, rights groups and independent media have come under growing pressure as next year’s election approaches. It could represent Hun Sen’s greatest electoral challenge in more than three decades in power.

One of China’s closest allies in the region, Hun Sen has increasingly ignored criticism from Western donors, whose budget support is no longer as critical as it during the early years of his rule, when Cambodia was little more than a failed state.

“We cannot allow foreigners to use Khmers to kill Khmers any more,” Hun Sen said on Monday, referring to the Khmer Rouge genocide that destroyed Cambodia in the 1970s. Hun Sen, 65, is a former Khmer Rouge soldier who switched sides.

Sokha was allowed to see a lawyer on Monday at his prison several hours from Phnom Penh near the border with Vietnam.

“I may lose freedom, but may freedom never die in Cambodia,” Kem Sokha was quoted as saying in a post on Twitter that was repeated by his daughter, Monovithya Kem.

WEST CALLS FOR RELEASE

The European Union called for his immediate release, based on the fact that he is meant to have parliamentary immunity, as an elected lawmaker.

“This arrest suggests a further effort to restrict the democratic space in Cambodia,” the EU said in a statement.

The U.S. State Department expressed “grave concern” at Sokha’s arrest on charges it said appeared to be politically motivated. It said in a statement it was also worried about other curbs on media and civil society.

Hun Sen has steadily increased his rhetoric against the United States, ending joint military exercises, expelling a U.S. pro-democracy group and on Sunday accusing Washington of conspiring with Kem Sokha.

U.N. High Commissioner for Human Rights Zeid Ra’ad Al Hussein said he was seriously concerned about the arrest, noting that it was on the basis of the video of a speech he had made in 2013 and which had been publicly available since then.

One of Kem Sokha’s deputies, Mu Sochua, said the opposition had done as much as it could and would not call for demonstrations because it believed in non-violence. She called on donors to help.

“There isn’t true peace. There has always been a false democracy,” said Mu Sochua, 63, who is one of three deputies to Kem Sokha in the Cambodia National Rescue Party (CNRP).

“The international community have been willing to close their eyes and play along with it. Right now all the red lines have been crossed,” she told Reuters in an interview in Phnom Penh.

An independent newspaper that had often been critical of Hun Sen published its last edition on Monday, saying it had been forced to close after being given one month to pay a crippling $6.3 million in back taxes .

Its final headline, on the arrest of Kem Sokha, was “Descent Into Outright Dictatorship”.