The paper's new ownership said Sunday in a statement that it was "fully committed" to upholding the 26-year-old newspaper's "principles/independence without infringing any relevant laws and regulations of the Kingdom of Cambodia", The Post reported.
According to Reporters Without borders, around 30 radio stations have also been closed down in recent months, after the opposition party did well in the June 2017 municipal elections, sparking a crackdown on independent media outlets.
Stuart White, the managing editor; Brendan O'Byrne, the business editor; Jenni Reid, the web editor; and Baliga all refused to comply and resigned.
Anant Baliga, a co-author of the article exposing the links of the new Chief Executive Sivakumar Ganapth to Cambodia's strongman Prime Minister Hun Sen, announced his resignation in a tweet.
Staff were reportedly told that all future articles would need to be approved by a new editor-in-chief before publication.
The Post staff's intention was "to make [Sivakumar] look bad and while ignoring the context and that is not acceptable", he said.
Critics mentioned the lack of an impartial press would have profound implications in Cambodia, a rustic that suffered underneath the brutal rule of the Khmer Rouge.
Last year, the leader of the largest opposition party was arrested on charges of treason and the party was later forced to dissolve.
"The prospects were already very bleak for a free and fair election" in July, Sam Rainsy added in a telephone interview from Paris, where he lives in exile. "Our article was written in an try to keep up the transparency and integrity of our paper as we now have carried out for greater than 25 years".
"All the undersigned express our disgust for this decision made in contradiction to the values of a free press".
Phil Robertson, the deputy Asia director at Human Right Watch, said the sale of the Phnom Penh Post means "the last pillar of press freedom has been toppled in Cambodia".
Bill, who is chairman and publisher of the Post Media Co., Ltd, said in a statement that Siva is a well respected newspaper man, with an experienced journalist background, and represents a strong investment group from Malaysia.
Kimsong told Southeast Asia Globe magazine that he was sacked because he had "allowed the printing of an independent story based on journalistic integrity".
The Phnom Penh Post, previously owned by Australian mining magnate, Bill Clough, was officially sold on Saturday to the Malaysian investor Sivakumar Ganapath, for an undisclosed amount, following a tax dispute with the authorities.
The Overseas Press Club of Cambodia (OPCC) voiced its concerns about the sale "to a Malaysian investor whose PR company is connected to Prime Minister Hun Sen".
Ganapathy's company website lists "Cambodia and Hun Sen's entry into the Government seat" as a former "project". "I think the odds are greater than 50/50 the paper's coverage will change - and for the worse", he said. His personal assistant, Krishna Kumar, said Monday in an email that he was unavailable for comment and would be out of the office for about two weeks.