The Overseas Press Club of Cambodia said in a statement that the move was “potentially dangerous and defamatory” and urged a retraction.
According to analysts, Hun Sen has not directly taken part in political campaigning since 1998.
According to the National Election Committee (NEC), some 8,000 disabled people have registered to vote.
The NDI is holding similar events in Takeo province’s Tropeang Thom Khang Cheung commune, on Wednesday, and Kratie province’s Svay Chreas commune, on Friday.
Thousands of district positions to be contested in June 4 ballots.
Depending on the source, 81.47 percent to 95 percent of Cambodia's 9.6 million eligible voters are registered.
Congressman Alan Lowenthal says U.S. Congress is concern over the arrest of opposition activists and officials in Cambodia.
The two-week campaign period will conclude on June 2, two days before the vote on June 4.
Almost 8 million people have registered to vote in the forthcoming commune council elections on June 4.