Thirty-eight people remain in unlawful detention after they were seized by authorities as they protested outside City Hall this week.
Hor Namhong told reporters Thursday that Asean leaders could help ministers of North and South Korea meet on the sidelines.
The demonstrators were seized Wednesday, where they had demanded the courts release eight representatives arrested earlier this month.
Around 300 families lost their homes in the Jan. 3 forced eviction of Borei Keila.
An estimated 20,000 Cambodians are trafficked throughout the region each year.
A UN spokesman said the organization was “aware of this development” but declined to comment further.
A US Embassy spokesman confirmed Baer had met with government and opposition officials, but declined to elaborate.
Cambodia and other Asean countries have adopted a draft of a charter for human rights that will see rigorous debate next month.
The site, at Phnom Bath mountain, is 50 kilometers outside the capital and lacks clean water, electricity, and health care facilities.
Prime Minister Hun Sen has said there will be no political deal and that Sam Rainsy’s cases are matters for the courts.
Campaigning for the Senate election, which is held for representatives of eight regions, will go from Jan. 7 to Jan. 27.
About 13,000 political officials of the Cambodian People’s and Sam Rainsy parties will vote in the election.