Opposition party leader Sam Rainsy has cited corruption in Cambodia to warn western governments and aid agencies to be wary in the wake of the Asian tsunami.

Rainsy told the Australian Broadcasting Corporation that widespread corruption prevented the $500 million in aid received each year from having much impact upon Cambodia's widespread poverty and social problems.

"We have to make sure that corruption will not help divert [tsunami] aid from those who are really in need of it," said Rainsy. "Donors must work together in order to ensure the effectiveness of that aid."