Toch Voeun, 54, a Sam Rainsy Party candidate for the commune elections, was gunned down at his home in Siem Reap's Ta Peam village on August 23.
The killing - the third in two months - followed the setting up by Prime Minister Hun Sen of a special security committee to ensure the safety and security of all electoral candidates .
Authorities said that no political motive could be ascribed to the latest killing and claimed it was the result of a personal dispute. Human rights NGOs dismissed this, saying it was definitely a political killing.
Voeun was shot with an automatic weapon and pronounced dead upon arrival at the hospital, making him the second victim from the opposition party. A Funcinpec candidate was murdered in a similar attack in July; another Funcinpec candidate survived another attack.
The Cambodian Human Rights Action Committee (CHRAC), which represents 18 local NGOs, said in a monitoring report dated August 29 that in addition to the latest killing, at least 82 cases of political threats and intimidation had been reported since January.
"Politically motivated cases have been threatening the freedom of people to take part in political activities, [which are] guaranteed by the constitution. In many cases, the perpetrators have not been brought to justice," CHRAC chairperson Sok Sam Oeun said. He added that this could seriously affect the process of free and fair elections.
Meanwhile, the National Election Committee (NEC) announced that 83 percent of voters registered during the process that concluded on August 19.
Though the figure is marginally higher than the target it had set before the registration process began on July 21, election watchdog Comfrel expressed concerns, saying lower turnout for registration could translate into still lower voter turnout on the polling day.
"A registration figure of 93 percent as achieved during 1998 general elections [would be] preferable," it said.
The preliminary voters' list will be posted by the NEC between September 20 and 24, followed by corrections or additions to finalize the electoral rolls by October 13.
Among the reported irregularities were cases of vote-buying. In Prey Sbat and Ta Suon villages of Takeo province, for example, Comfrel said that CPP activists "gathered local voters and offered them gifts, [while] asking them to swear by drinking oath water that they will adhere (sic) to the party. Similar cases were reported from some communes in Banteay Meanchey as well."
"[The practice] is an abuse of article 8 of the NEC's regulations and procedures for commune elections," Comfrel said, adding that the run-up to 1998 general election had seen similar large scale influencing of voters by the CPP.