Cambodia's former leader Hun Sen and his family are set to consolidate power after a vote over the weekend.

Hun Sen, who served as prime minister for 38 years, is believed to have won a seat in Sunday's Senate election. The incumbent leader, his son Hun Manet, says the ruling Cambodian People's Party swept 55 of 58 contested seats. Official results have yet to come out.

Hun Sen handed over power to his eldest son after last year's general election, but stayed leader of the CPP. Now, he is expected to be tapped as president of the upper house, serving as acting head of state in the event of the king's absence.

In Sunday's poll, lower house lawmakers and local assembly members cast ballots. Most eligible voters were CPP members because opposition parties were barred from running in last year's National Assembly election.

Western countries and the United Nations have voiced concerns over the legitimacy of the country's democratic process.

The election came after Prime Minister Hun Manet's younger brother was appointed as a deputy prime minister last week, ensuring key government posts are filled with members of Hun Sen's family.