Mak Remissa / EPA

Foreign tourists look at photographs of Khmer Rouge victims on display at Tuol Sleng Genocide Museum (S-21 prison) in Phnom Penh, Cambodia, on Jan. 11, 2012.

Updated 1:00 p.m. ET Friday:  The court’s National Co-Investigating Judge, You Bunleng, responded on Friday to criticisms lodged against him by his counterpart, International Reserve Co-Investigating Judge Judge Laurent Kasper-Ansermet. The Cambodian judge said Kasper-Ansermet had ill intentions for issuing the statement without his knowledge, claimed he was trying “to confuse public opinion” over his alleged opposition to further investigations, and noted that the Swiss judge was not authorized to undertake any procedural actions while no one has been named to the post of International Co-Investigating Judge.

A judge at Cambodia's genocide court said Thursday that he will reverse a decision to end a controversial investigation into the role of more Khmer Rouge leaders in the 1970s "killing fields" regime that left nearly two million people dead, amid claims by critics that the government had exerted pressure to stop further queries.

The investigation of five unnamed suspects -- covered by what is known as cases 003/004 -- has been troubled since it began in 2009, with allegations of political interference by the Cambodian government and a lack of judicial independence.

An international judge tasked to work on that investigation resigned last year after government ministers made statements about the court not pursuing more trials following the completion of those of four of the regime’s top surviving leaders. Those trials are ongoing.

The court's press office released a statement from another international judge, Laurent Kasper-Ansermet of Switzerland, early Thursday stating that he would order the judicial investigation into case 003 to resume. That case was closed last April, sparking an outcry over how deep the tribunal's examination of the 1975-1979 regime would go.

Kasper-Ansermet's bid to reopen the investigation was the "fresh breath of U.N. air we have been demanding," Theary Seng, a Khmer Rouge survivor and an advocate for victims, wrote to msnbc.com. She noted his "unexpected assertiveness regarding his pursuit of the political(ly) controversial cases 003/4," which she alleged were "expressly blocked by the government."

"The U.N. and the Cambodian government are heading for a showdown because of the unexpected flexing of muscles by the U.N. vis-a-vis the Cambodian government," she added.

Kasper-Ansermet's statement cast a light on the inner workings of the tribunal, which has seemingly been mired in internal tussles since it began operations in 2007, following a decade of halting negotiations between the government and the U.N. over the court's structure and functioning. The Extraordinary Chambers in the Courts of Cambodia is a hybrid of international and Cambodian judges.

The statement detailed how Kasper-Ansermet's attempts to make submissions in the disputed cases were rebuffed by his Cambodian counterpart, who said the Swiss judge had not been officially appointed to replace the one who resigned last year, and by the pre-trial chamber, which said he did not have the qualifications to assume the post.

It also noted that the chamber failed to notify the judge of its decision on the submissions, raising "serious concerns about the lack of impartiality" of its president, the statement said, and called for him to step down from any proceedings related to case 003/004.

Clair Duffy, Khmer Rouge Tribunal Monitor for the Open Society Justice Initiative, said the resumption of the case was an "important development" for victims.

"The premature closure of the 003 investigation was particularly worrying because it came against the background of opposition to further investigations from the Cambodian government," Duffy wrote to msnbc.com. "The proper handling of these two cases still under investigation (cases 003 and 004) will be a litmus test of the court's ability to meet the basic standards of international law that it was set up to achieve, in order to bring justice for victims of the Khmer Rouge, and to promote future adherence to the rule of law in Cambodia."

Under the Khmer Rouge, nearly one quarter of the country’s population – or at least 1.7 million people – died from execution, disease, starvation and overwork, according to the Documentation Center of Cambodia.

The ultra-Maoist group strived to create an agrarian utopia (and called their effort a return to “Year Zero”), forcing city dwellers to rural areas to work on large farms, destroying money, shuttering schools and prohibiting religious worship in the predominantly Buddhist country. Intellectuals, or those with an education, were often deemed their enemies and targeted for execution.

Intensifying border skirmishes with neighboring Vietnam led the Vietnamese to invade Cambodia and thereby end Khmer Rouge rule.

The decision comes a week after the tribunal rejected an appeal for acquittal by Kaing Guek Eav, also known as Duch, a prison chief who oversaw a torture center where at least 12,000 people died. The court instead increased his sentence from 19 years to life.

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