EMBATTLED opposition leader Sam Rainsy says he plans to file fresh complaints against Prime Minister Hun Sen in a US court accusing him of involvement in a 1997 grenade attack on an opposition rally that left 16 dead and more than 100 injured.

The politician, who is currently living in self-imposed exile said he would unveil more details of the complaint at a videoconference from France at the Sam Rainsy Party’s headquarters on Friday.

In a statement issued Tuesday, Sam Rainsy promised to initiate “new judicial proceedings in New York against Mr Hun Sen and his subordinates in relation to a deadly 1997 grenade attack in Phnom Penh and an investigation by the US Federation Bureau of Investigation”.

On March 30, 1997, four grenades were thrown at a rally held by the opposition Khmer Nation Party – the predecessor to the SRP – killing 16 and injuring scores of bystanders.

Sam Rainsy has long alleged the involvement of Brigade 70, Hun Sen’s personal bodyguard.

The complaint came as Hun Sen departed for New York, where he will attend the 2nd ASEAN-US Leaders’ Meeting on Friday.

It recalls a similar lawsuit filed in US and French courts in 2005, ahead of another of Hun Sen’s visits to New York

Ou Virak, president of the Cambodian Centre for Human Rights, said that during the 2005 visit – also a period when Sam Rainsy was living in self-imposed exile – US officials served Hun Sen a subpoena, prompting negotiations that paved the way for Sam Rainsy’s return to the country.

Sam Rainsy could not be reached for comment in Europe, but in an interview with Radio Free Asia, he said the legal process had commenced. Hun Sen had “implored” him to withdraw the 2005 complaint, he said, but added that it could be re-filed to the courts at any time.

“If I want to file my complaint in the US and France at any time it is OK, and Mr Hun Sen will be scared again. It has already been started,” he told RFA.

Government officials said that they were unfazed by the plans to file a lawsuit, and predicted that it would only attract more complaints from the government.

“If he sues like this, it is easy since we can continue to file more complaints” against Sam Rainsy, said Information Minister Khieu Kanharith. He said the 1997 grenade attack had already been investigated by the FBI, and that the government was “not at all afraid” .

Phay Siphan, spokesman for the Council of Ministers, said Sam Rainsy was trying to turn his ongoing legal battles into a personal issue.

“This is not the first time – very often he has insulted the prime minister,” but Hun Sen, as a head of state, would be immune from any legal challenge, he said.

Hang Chhaya, executive director of the Khmer Institute for Democracy, said it was unclear whether the premier could be affected by a US lawsuit. “It’s not a reliable option, but it’s a last resort,” he said.

Despite the weight of charges facing Sam Rainsy, he said, the politician would rise again, since he was still vital to his party – and the government’s own democratic legitimacy.

“At the end of the day, we still need to have the opposition in the Cambodian political system,” he said. “I don’t think it’s done as far as Sam Rainsy is concerned.”