Two relatives charged with attempting to pull out a boundary marker on the Vietnam border in Tbong Khmum province accidentally damaged the post by using it to steady themselves on a drunken walk home, their family says.

Detained on August 31, Som Vat, 34, and his brother-in-law Sok Ko, 25, have been charged with “intentional damage with aggravating circumstances” and sent to the provincial prison for allegedly trying to pull out the marker in Memot district.

However, Chron Sreytouch, 31, wife of Vat, said the men did not deliberately attack the post – nor were they concerned about alleged Vietnamese encroachment – but had consumed two to three litres of wine and were trying to walk home.

“The post is near the road and at 6pm, the two [men] left the drinking place and they fell near the post, but they did not pull the post out,” Sreytouch said.

“They just tried to hold the fence of the post to stand up, and then they rode the motorbike off from there. They were obviously drunk and had no intention to do that.”

After getting a request from the family, rights groups Adhoc will provide a lawyer.

The border has long been a politically sensitive topic, and in 2010, opposition leader Sam Rainsy was sentenced in absentia to two years in prison for uprooting border markers while protesting alleged encroachment in Svay Rieng province.

But after inspecting the site, Adhoc coordinator Neang Sovath said the men’s story appeared genuine, noting they didn’t own land in the area.

Memot district police chief Hong Kimhoeun said border officials were responsible for the arrest, but said the pair had attempted to pull out the post, which was now “shaky”.