Sam Rainsy is currently on a visit to the US to build political support for his party, which holds 26 seats in the National Assembly.
The two governments are currently in the process of marking the borders according to agreements from 1985 and 2005.
The National Assembly and Senate established their representatives on a new anti-corruption council on Tuesday.
Cambodian and Thai troops engaged in a brief exchange of gunfire on Tuesday, but neither side reported injuries.
Donor countries and international agencies offered Cambodia up to $1.1 billion in aid this year, which came amid calls for reform.
Residents here say they are increasingly loosing long-term farmland to concessions for plantations of rubber and cashew.
Cambodia is considering increasing formal diplomatic relations with Iran, including establishing an embassy in the capital Tehran.
Sam Rainsy, who is on a US tour to build political support, said he was not confronting Prime Minister Hun Sen, but rather Vietnam.
Global Witness also revealed a series of what it called "high level corruption and governance failure" over the last 18 months.
Critics of the anti-corruption law have said it lacks the teeth to root out the country’s endemic corruption.
Mu Sochua said she would not pay the fine.
Cambodia insists it has been transparent in managing state revenue.