THE acting international co-prosecutor at the Khmer Rouge tribunal on Monday requested the investigation of five more suspects in two separate filings, one of which covered crimes he said constituted genocide.

The filings from William Smith were submitted on the same day Prime Minister Hun Sen warned that the pursuit of additional prosecutions risked sparking civil unrest that could claim up to 300,000 lives.

They were the second and third introductory submissions from prosecutors. The first, submitted in July 2007, led to the indictments of the five Khmer Rouge leaders currently in custody.

In a statement Tuesday, Smith said the submissions covered 40 "distinct factual situations" of murder, torture, unlawful detention, forced labour and persecution.

The allegations described in both submissions would amount to crimes against humanity and violations of Cambodian law, whereas those in the third - which covers 32 of the 40 factual situations - would also amount to genocide, he said.

The co-prosecutors also argued in July 2007 that crimes detailed in the first submission constituted genocide, though none of the five regime leaders mentioned were ultimately charged with it after investigations concluded.

The tribunal opened the door to new investigations last week by announcing that the five-person Pre-Trial Chamber had failed to resolve a nine-month disagreement between the international co-prosecutor, who pushed for the investigations, and the national co-prosecutor, who argued against them, citing concerns about national stability. The chamber voted three-to-two against them. The tribunal's internal rules held that the proposed investigations would go forward in the absence of a supermajority, or four-to-one vote.

Smith told the Post Tuesday that the Pre-Trial Chamber decision "obligated me to immediately forward the two submissions to the co-investigating judges". National co-prosecutor Chea Leang said Tuesday that Smith "had every right" to go forward with the submissions and declined to comment further. Smith said in the statement that he had "no plans to conduct any further preliminary investigations into additional suspects" at the tribunal.

The submissions - and consequently the names of the five suspects - are confidential.

One former cadre who has been repeatedly mentioned as a likely suspect said he agreed with Hun Sen's repeated claims that more prosecutions could spark unrest.

Meas Muth, former secretary of Central Committee Division 164, which included the Khmer Rouge navy, said by phone from Samlaut that "further prosecutions would lead to conflict".

The former military commander is one of two men included in the 2001 report on prosecution candidates - written by Stephen Heder and Brian D Tittemore - who is still alive and has not been indicted.

Sou Met, former secretary of Central Committee Division 502, which included the air force, is the other.