Ex-political prisoner Meach Sovannara says the Cambodia National Rescue Party will remain united despite a crackdown by the ruling party.
Former CNRP members barred from politics may not take part, Cambodian authorities say.
Imports from the two nations had nearly doubled in the past five years, while prices declined.
Meanwhile, two former opposition figures are allowed to re-enter politics after applying to Cambodia's king for a 'pardon.'
But a critic of strongman PM Hun Sen say such a move is conceivable given his ties to her family.
They also urge the prime minister to intervene in the case, citing promises of increased media freedom.
Observers say the visit demonstrates financial and military support for Prime Minister Hun Sen’s regime.
Grassroots environmental group criticizes government efforts to stop tree poachers.
Acting opposition leader Sam Rainsy urges those banned to refrain from falling into a ruling party ‘trap.’
But he falls short of inviting the now-dissolved main opposition party for talks.
Only around 700 families remain and will be relocated by July, an official says.
Prime Minister Hun Sen had earlier suggested the move would encourage the opposition to defect.