By Prak Chan Thul
PHNOM PENH (Reuters) - Cambodian Prime Minister Hun Sen vowed on Monday to resist foreign interference, following international criticism of the arrest of his main rival for treason and a widening crackdown on his critics.
The United States and the European Union condemned the detention of opposition leader Kem Sokha, who is accused of plotting with U.S. support, and steps against the media that forced the independent Cambodia Daily to shut on Monday.
"We can’t allow any group to destroy the peace we hold in our hands by being the puppets of foreigners," Hun Sen said at the opening of a new mosque in Kompong Cham province.
"We cannot allow foreigners to use Khmers to kill Khmers any more," he said, referring to the Khmer Rouge genocide that destroyed Cambodia in the 1970s. Hun Sen, 65, is a former Khmer Rouge soldier who switched sides before it was driven out.
Opposition politicians, rights groups and independent media have come under growing pressure in the run-up to an election next year in which Hun Sen could face the greatest electoral challenge of 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 during the early years of his rule when Cambodia was little more than a failed state.
Sokha was arrested in a raid on his home early on Sunday.
He had still not been allowed to see his lawyer by Monday, his daughter, Monovithya Kem, said on Twitter.
"We don't know his condition, whether he's safe," she said.
The European Union called for his immediate release, based on the fact that he is meant to have parliamentary immunity, as an elected lawmaker.
"Along with recent actions by the authorities against NGOs and some media organizations, 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.
Spokeswoman Heather Nauert said the steps "raise serious questions about the government's ability to organize credible national elections in 2018 which produce an outcome that enjoys democratic legitimacy".
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.
The Cambodia Daily newspaper, which published its last edition on Monday, said 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".
(Writing by Matthew Tostevin)