THE Inter-Parliamentary Union (IPU) is interfering in Cambodia's internal affairs by sending an observer to the upcoming trial of Sam Rainsy Party (SRP) lawmaker Mu Sochua, a senior official said Tuesday.

"Although the IPU is an international parliamentary body, it should not interfere in Cambodia's legislature, executive or judiciary. If they interfere in this issue, it will be a violation of Cambodian sovereignty," Nguon Nhel, first deputy president of the National Assembly, told the Post Tuesday.

The Geneva-based IPU announced this week that it would send former Philippines Senate president Franklin Drilon to sit in on Mu Sochua's case at Municipal Court on Friday, during which she will face defamation charges filed by Prime Minister Hun Sen.

"[The] IPU is coming to observe my case because it is a big story," Mu Sochua said Tuesday. "They are coming to investigate my story because they have written several letters to National Assembly President [Heng Samrin], but [he] has not responded."

Ingeborg Schwartz, programme manager for human tights at the IPU, said Wednesday that "an observer" would come to Cambodia to "examine" the case. She declined to comment on whether the IPU would conduct an investigation, saying the case was confidential.