Former Olympic rower Rob Hamill has announced plans to file a civil party application at the Khmer Rouge tribunal in relation to the court’s controversial third and fourth cases.

The New Zealander’s application targets former Khmer Rouge navy commander Meas Muth and air force commander Sou Met, and follows a similar application lodged by local activist Theary Seng on Monday, the first in relation to Cases 003 and 004.

These cases, still in the preliminary investigation stage, feature five suspects who have not yet been arrested or charged and whose identities remain confidential. Theary Seng said this week, however, that she was confident Meas Muth and Sou Met were among those being investigated based on public documents and her own research.

Hamill’s brother Kerry was captured by the Khmer Rouge in 1978 while sailing with friends in the Gulf of Thailand before being taken to S-21 prison in Phnom Penh and executed. Rob Hamill appeared to testify about the ordeal in 2009 during the tribunal’s first trial, that of former S-21 prison chief Kaing Guek Eav, better known as Duch.

Speaking by phone from New Zealand, Rob Hamill said yesterday that his new civil party application had been inspired by Theary Seng’s, and that he hoped it would help end “the stalling of the process” in Cases 003 and 004.

Prime Minister Hun Sen and other Cambodian officials have expressed opposition to these cases, which have apparently progressed little since they were first submitted for investigation by prosecutors in 2009.

“The experience of the court I’ve found very rewarding, and from a moral perspective, I think it’s been a great process to go through, with the exception of this last case,” Hamill said.

“I shouldn’t have to be in a position where I have to speak out to reignite a process that should be moving along.”

Tribunal officials reacted angrily to Theary Seng’s announcement this week, declining to confirm whether Meas Muth and Sou Met are indeed being investigated and calling the allegations “reckless” and “irresponsible”.

United Nations court spokesman Lars Olsen said yesterday that the court “has already said publicly what its reaction is to the naming of individuals in the public domain”.

“I find it unfortunate that it seems like a practice of naming individuals based on speculation is continuing by another civil party applicant,” Olsen said.

Both Hamill and Theary Seng, whose loved ones were killed under the Khmer Rouge regime, said in statements this week that they held Meas Muth and Sou Met responsible for the deaths of their family members, for the role the men played in the “common purpose and design in the arrests and executions, specifically in their respective divisions and generally for the whole of Cambodia”.

Hamill said yesterday that Meas Muth bore particular responsibility for the death of his brother, who was captured by the Khmer Rouge navy.

“I see Meas Muth’s role as critical, almost potentially more important than the role Duch played, in the sense that his role … that he played to take my brother’s freedom away was the critical moment in my brother’s life,” Hamill said.

“If he had shown an ounce of human decency at that time, our lives as a family here in New Zealand would have been completely different.”