Phnom Penh, Cambodia (CNN)The Cambodian government is coming under widespread criticism after the leader of the political opposition was arrested and accused of treason.
"Kem Sokha, president of the Cambodia National Rescue Party (CNRP), has been accused of involving foreigners in secret plans against the Kingdom of Cambodia" the Phnom Penh Municipal Court said in a statement. "This is considered treason."
Sokha's lawyer Chann Chen confirmed to CNN Wednesday that his client had been officially charged with treason. He said he hadn't been able to meet him since the charge was laid.
"(We) are currently trying to meet with him. We expect legal proceedings to continue in the typical way," he said.
If found guilty, Sokha could face 15 to 30 years in prison.
Prime Minister Hun Sen's government has accused the opposition leader of plotting with the United States to topple the government. Sokha was arrested at his home in the capital of Phnom Penh in the early hours of Sunday morning and taken to Correctional Center 3 over 100 miles away, according to Mu Sochua, CNRP deputy president.
"It's not necessary to take him to such a remote prison," said Sochua. "It's difficult for his lawyers, for his colleagues and his family to visit him." Sochua also denied there was any plot. "Kem Sokha has committed no crime. His only crime is to promote democracy and wish for the rule of law within democratic principles."
Analysts note that his arrest comes soon after his party made significant gains in the local elections in June. "The local election results are a strong indicator of a swing towards the CNRP which worried the ruling party," said Virak Ou, a human rights activist and economy analyst.
US, EU and China react
With general elections scheduled for June 2018, there are concerns about what lies ahead.
Indeed, news of Sokha's arrest was met with dismay by the US and the European Union. In a statement, the US State Department said the arrest seems "politically motivated" and casts doubt on Cambodia's ability to "organize credible national elections in 2018 which produce an outcome that enjoys democratic legitimacy."
The statement did not address accusations of trying to topple the Cambodian government. However, US embassy deputy spokesman David Josar directed CNN to a statement he gave The Phnom Penh Post -- an English-language daily -- on August 30 that said, "any suggestion that the United States is supporting or has supported revolution is categorically false."
In a September 3 statement, the European Union termed the arrest "a dangerous political escalation." It also said, "This arrest suggests a further effort to restrict the democratic space in Cambodia and the space for independent reporting, comment and criticism."
Sokha's predecessor, former CNRP leader Sam Rainsy, also issued a statement from his current home in France, where he is in exile. He called the Cambodian government's allegations of treason "senseless."
"Is it 'treachery' to want a democratic change for one's country and to work peacefully to achieve it?" Rainsy said.
When asked about the opposition in an interview earlier this year, spokesman for the Cambodian government's Council of Ministers, Phay Siphan, was defiant. "I don't care about critics because they are not Cambodian and they are biased already," he said. "Who does Cambodia belong to? Kem Sokha or the rule of law?"
"Sam Rainsy ran away from his obligations and Kem Sokha has [conspired against us]; this is a problem with the opposition party, not Cambodia," he said. He dismissed comments from CNRP leaders as "purely propaganda and not factual."
In a September 3 speech to a gathering of garment workers, Prime Minister Hun Sen -- who has led Cambodia for 32 years -- said he had to arrest Sokha due to the seriousness of the situation.