In what could lead to a sequel to his five-hour speech in the National Assembly in 2012, Prime Minister Hun Sen has been asked by an opposition lawmaker to answer questions in parliament over alleged border encroachment in Mondulkiri province.

Mao Monivann, a Cambodian National Rescue Party lawmaker, visited the Vietnamese border last month. Since returning, he has drafted a letter to National Assembly President Heng Samrin asking Hun Sen to explain the status of the Dak Dam checkpoint in O’Raing district.

“A speech from [Hun Sen] … stated that Dak Dam … has not yet been agreed upon by both countries,” says the letter, dated Tuesday. Vietnam, the letter alleges, has continued to treat the area as its own, including constructing a road there, despite a 2005 treaty leaving ownership unresolved.

“Please, Prime Minister, clarify this for Cambodian citizens,” Monivann wrote.

In August 2012, Hun Sen took centre stage at the National Assembly to address concerns over a demarcation deal with Vietnam. In a 320-minute address – supposedly a personal record – he explained that the two countries had agreed to compensate each other with unoccupied land for villagers that lay in the opposing country’s boundaries.

The speech was littered with vitriol against the opposition. At the time, opposition lawmaker Son Chhay said it was the first time in almost 20 years that Hun Sen had answered a written question in parliament.

Var Kimhong, the senior minister in charge of border affairs, said yesterday that Cambodia was still working towards resolving the Dak Dam issue.

“We do not have a plan to go there. We have a plan to have round-table talks,” Kim Hong said.

He added Hun Sen was unlikely to address the issue in parliament and suggested he may do it himself.

The Vietnamese Embassy in Phnom Penh could not be reached.