Cambodia's beloved former monarch Norodom Sihanouk, who died aged 90 last month, will be cremated on Feb 4 following an elaborate ceremony, Prime Minister Hun Sen said on Monday.

The cremation will be preceded by a procession on Feb 1 that will see Sihanouk's coffin carried from the royal palace in Phnom Penh to a funeral pyre in a nearby park, the premier said in a speech on national radio.

"It will be a big ceremony," Hun Sen said.