Cambodia has been warned that it may lose its EU trade benefits due to its human rights and political freedoms record.

The European Union expressed concern at the human rights situation in Cambodia as it gave the government a one-month deadline to respond to a report on its investigation before deciding whether to suspend trade benefits.

The EU has threatened to suspend the trade preferences over a crackdown on the opposition, non-governmental organisations and the media by the government of Prime Minister Hun Sen, who has ruled the Southeast Asian country of 16 million people for more than 34 years.

The European Commission, the EU’s executive branch, said it had finalised its preliminary report on suspending trade preferences and sent it to Cambodian authorities. It did not publish the report.

“We are very concerned about the human rights situation there,” EU trade commissioner Cecilia Malmstrom said on Twitter. “The Cambodians now have one month to respond and we will make our final decision in Feb next year.”

Foreign Ministry spokesman Koy Kuong confirmed the report had been received but said there was no comment for now.

In a sign of growing pressure on Cambodia, the government relaxed house arrest conditions at the weekend on opposition leader Kem Sokha, but did not withdraw treason charges against him.

The EU has threatened the preferential trade terms that Cambodia enjoys under its Everything But Arms (EBA) scheme that gives 47 of the world’s poorest countries duty-free, quota-free access for all products except arms and ammunition.

The EU accounts for more than one-third of Cambodia’s exports.

It acted after the arrest of Kem Sokha and the banning of the opposition Cambodia National Rescue Party before elections last year that were won convincingly by Hun Sen’s party but dismissed by western countries as a farce.

Any European Commission decision to withdraw trade preferences would still need approval by the European Parliament and EU member states.

Kem Sokha’s fellow opposition leader Sam Rainsy, 70, met Malaysian MPs on Tuesday in a bid to rally support in Southeast Asia.

Rainsy and Kem Sokha, 66, have been locked in a long struggle against Hun Sen, 67, a former Khmer Rouge commander.

Rainsy has lived in self-imposed exile since 2015 to escape a defamation conviction and charges he says are political.

He said he had planned to return home via Thailand at the weekend to rally opposition to Hun Sen but was barred from boarding a Thai Airways flight from Paris. More than 50 people have been arrested since Rainsy said he intended to return home.

The EU has travelled to nearby Myanmar to raise concerns about human and labour rights there but has stopped short of starting the process to withdraw EBA preferences.