By Prak Chan Thul and Amy Sawitta Lefevre
PHNOM PENH (Reuters) - Cambodia's Supreme Court on Thursday began its final session to decide whether to dissolve the main opposition Cambodia National Rescue Party (CNRP), thus ensuring victory for Prime Minister Hun Sen's ruling party in next year's general election.
A verdict is expected later in the day, amid an increasingly tense political situation and a campaign by the ruling Cambodian People's Party (CPP) to crush the opposition ahead of the vote.
If the court rules for dissolution, 118 members of the opposition party will also be banned from politics. More than half its members of parliament have already fled Cambodia, fearing a crackdown by Hun Sen.
Such a ruling would leave "no credible political opposition in Cambodia" for the first time since 1993, one senior diplomat based in the Cambodian capital told Reuters.
In that year a U.N.-run election produced a shaky coalition between Prince Norodom Ranariddh and Hun Sen, a former Khmer Rouge guerrilla installed as prime minister in the mid-1980s by the Vietnamese.
"The processes in the early 'nineties left Cambodia with a lively civil society and the freest press in Southeast Asia and there is a possibility of a lot of that going," said the diplomat, who declined to be identified because he was not authorized to comment.
Dozens of police guarded the court, its exterior painted yellow with gold accents, along with some officers from Hun Sen's personal bodyguard unit, although there has been no indication of any planned protest. Traffic flow was normal.
On Wednesday, Cambodia's opposition said it did not think it could escape dissolution.
The judge who heads the Supreme Court, Dith Munty, is a member of the permanent committee of the ruling party and a longtime Hun Sen loyalist.
The 2018 election had been shaping as possibly the biggest challenge to Hun Sen's leadership, after his opponents unified behind the CNRP.
Hun Sen has stepped up measures against the opposition. In September, CNRP leader Kem Sokha was arrested in Phnom Penh and charged with treason.
(Writing by Amy Sawitta Lefevre; Editing by Clarence Fernandez)