Opposition Senator Hong Sok Hour is in hiding after Prime Minister Hun Sen yesterday demanded his “urgent” arrest over a “treasonous” Facebook post.

Speaking at a graduation ceremony in Phnom Penh yesterday morning, the premier accused the Sam Rainsy Party (SRP) senator, a dual Cambodian-French citizen, of committing treason by posting a “fake” section of the 1979 Cambodia and Vietnam border treaty on Wednesday.

The premier then ordered National Police Commissioner Neth Savoeun to detain Sok Hour and asked Minister of Justice Ang Vong Vathana to request the Senate revoke the parliamentarian’s immunity.

“Whatever price, the government has to take action.… This is treason; I can say it like this,” Hun Sen said.

“This is a real crime and an arrest must be made urgently.… Embassies must not interfere. This is a crime of national betrayal.”

The calls for arrest come after similar demands by the premier last week saw three opposition activists detained and charged over an anti-government protest that turned violent last year.

The opposition sees the crackdown as a response to its ongoing campaign against alleged Vietnamese border encroachment and its accusations the government has ceded land by using the wrong map to demarcate the frontier.

As of yesterday afternoon, Teav Vannol, also a senator for the SRP, which still exists as a separate entity at the Senate and commune level despite the merger that created the Cambodia Rescue Party in 2012, said that Sok Hour was in a “safe place” contrary to early reports he was seized at CNRP party headquarters.

During his speech, the prime minister cautioned foreign embassies against providing refuge and warned the opposition that shielding the lawmaker risked further disputes between the parties.

He also demanded Phnom Penh International Airport block Sok Hour from fleeing and moved to dismiss any criticism that his actions were arbitrary.

“The royal government does not arrest this man or that man as it wishes,” he said.

“Regardless of what nationality anyone has, [we arrest] because this is a serious case.”

Shortly after the premier’s speech, the government, in a statement, said Sok Hour had seriously threatened national security, political stability and Cambodia’s territorial integrity by posting a fake version of Article 4 of the 1979 Cambodia-Vietnam treaty.

According to the statement, the fake article stated the countries would negotiate and sign an agreement to “eliminate” national borders, while the real version stipulated both countries would work to “define” the border and ensure peace.

Sok Hour’s colleagues said that the text in his post had been circulating online for some time, and that the senator had simply reposted it.

Both the text and an accompanying video from Sok Hour have been taken down.

Article 104 of the constitution grants senators broad-based immunity from arrest, except in cases when the body itself approves, or if a senator is caught red-handed in a criminal act.

In his speech, Hun Sen noted it wouldn’t be difficult to strip Sok Hour’s immunity, because the Cambodian People’s Party held more than the required two-thirds majority in the Senate.

And initially, according to the SRP’s Vannol, the ruling party moved to hold a full Senate session this morning before deciding to postpone it yesterday afternoon.

Senate Secretary-General Um Sarith said the upper house had not yet received a request from the Justice Ministry to revoke Sok Hour’s legal protection.

National Police spokesman Kirt Chantharith and Interior Ministry spokesman Khieu Sopheak said they weren’t aware of an arrest warrant issued for Sok Hour.

CNRP spokesman Ou Chanrith called the premier’s allegations of national betrayal baseless, and said Sok Hour’s immunity meant he shouldn’t face arrest orders.

“This is not a real crime,” Chanrith said.

In a statement, SRP president Kong Korm also rejected the idea that Sok Hour’s post was treasonous but said any inaccuracies should be cleared up.

In June, Sok Hour obtained maps from France which the CNRP says are the constitutionally recognised “Bonne” maps that should be used in demarcation.

Sebastian Strangio, author of Hun Sen’s Cambodia, said that after months of appearing flexible on the border issue, the prime minister was “drawing a line in the sand”.

“I think by ordering Hong Sok Hour’s arrest for what is a relatively insignificant transgression is a way of signalling there are limits about what can be said about this issue now,” Strangio said.