President Tran Dai Quang died in a military hospital in Hanoi of a “serious illness despite efforts by domestic and international doctors and professors,” Vietnam Television said.
The decision was announced on the same day that Hun Manet was appointed as the commander of the army.
Ahead of the polls, many rural communities that lost land were promised solutions if they voted CPP, but farmers fear they will now get little help.
The joint announcement on Wednesday marked the end of scheduled talks between the two states.
Hun Sen said recently that Cambodia was sovereign and independent and would not bow to international pressure over its rights record.
The CPP won all 125 seats in the National Assembly in July after it oversaw the banning of the country’s main opposition party, the Cambodia National Rescue Party.
Cambodia and China established diplomatic ties some 60 years ago, cultivated in large part by the late King Norodom Sihanouk.
At a meeting on Thursday at the Heritage Foundation, speakers said the newly one-party parliament did not reflect voters’ wishes to see pluralistic democracy in the country.
The NEC said that it would also remove those who had been reported deceased in the same period and an additional 100,000 names.
William Heidt, the US ambassador, told VOA Khmer that he hoped Cambodia would move towards a more “open” political system in the coming year.
The EU is Cambodia's largest export market, with garment exports to the EU alone amounting to about $700 million annually.
Hun Sen said countries outside of the region were “always slapping our heads” and “getting involved in regional politics,” according to a video posted on his Facebook page.