A BACKLOG of unsolved violent crimes involving high-ranking perpetrators could overshadow attempts to bring senior Khmer Rouge leaders to justice, Human Rights Watch said Monday.

In a statement released to coincide with the 12th anniversary of a 1997 grenade attack that tore apart a peaceful political rally in the capital, the New York-based organisation called the unsolved case - and others like it - an "open wound" that sustained the Kingdom's culture of legal impunity.

"The perpetual failure to address this crime has made March 30 Impunity Day in Cambodia. This anniversary, on the day the Khmer Rouge trials are beginning, shows how far Cambodia has to go toward holding human rights abusers accountable," said Brad Adams, Asia director at Human Rights Watch, in the statement.

The group also claims military officers suspected of involvement in the grenade attack have since been promoted to plum posts in the government and Royal Cambodian Armed Forces.

Huy Piseth, then commander of Brigade 70 - Prime Minister Hun Sen's personal bodyguard unit - was appointed to an undersecretary of state position in the Ministry of Defence, while his deputy Hing Bunheang was appointed to the post of deputy commander-in-chief of the RCAF in January. Brigade 70 troops were deployed at the rally on the day of the attacks, the statement said.

But Ministry of Interior spokesman Khieu Sopheak told the Post that the ministry has a "strong commitment" to maintain investigations into all unsolved cases.

"We have never received orders from the prime minister to close the cases," he said Tuesday. "All of the cases are still open and proceeding according to the law, so [they] have no influence on the trial of the Khmer Rouge leaders."

Political will needed

UN rights representative Christophe Peschoux said that continuing political interference in the domestic courts was "closely connected" to the legitimacy of the Khmer Rouge trials and that only political will could end the culture of impunity.

"It requires a political willingness on the part of the government ... to let the courts - whether in Kampong Thom or the ECCC - decide [cases] on the basis of evidence and law," he said.