Government spokesman Khieu Kanharith said counting was ongoing but the CPP had good preliminary figures on which to base its estimate.
"At this stage, the CPP has 90 seats, the Sam Rainsy Party has 26, then Funcinpec has two, the Norodom Ranariddh Party two and the Human Rights Party three, but these are not final figures," he said Monday.
The biggest loser appeared to be the royalist Funcinpec Party, which has continued a downward slide since winning the 1993 elections despite sacking its disgraced former leader, Prince Norodom Ranariddh, last year.
Ranariddh, in exile in Kuala Lumpur after being found guilty of making a private sale of Funcinpec's multimillion-dollar headquarters and being sentenced to 18 months in jail in absentia, set up his own eponymous party.
Funcinpec spokesman Ork Socheat declined comment on the royalists' terrible showing, saying he was out of town.
Before Sunday's polls, the CPP held 73 seats, Funcinpec 26 and the Sam Rainsy Party 24.
Prime Minister Hun Sen has vowed to keep coalition partner Funcinpec and swore never to form an alliance with the Sam Rainsy Party although with such a resounding victory, his party has no need to collaborate with any party.
The monolithic CPP, led by Hun Sen and structured on a Communist model, was always expected by analysts and the party's own pollsters to win handsomely, but the results surpassed expectations.
An estimated 8 million people were registered to vote in the first national elections in five years in the country of more than 14 million people. The CPP claims 5 million members.
Hun Sen has ruled for 23 years but is enjoying a new surge in popularity because of Cambodia's rapid economic growth, which the International Monetary Fund placed at around 10.5 per cent in 2007.//dpa