Thousands of Cambodians were joined by international leaders to pay their last respects at former King Norodom Sihanouk's cremation ceremony.

Crowds gathered clutching photos of Sihanouk, a much-loved figure who reigned during the country's struggle for independence, but was powerless to prevent decades of war.

The current King Norodom Sihamoni and Sihanouk's widow, Queen Monineath, wept during the cremation as Cambodians poured into the capital to mourn the "king father", as Sihanouk is known.

Foreign leaders, including French Prime Minister Jean-Marc Ayrault and Thai Prime Minister Yingluck Shinawatra, attended the cremation ceremony.

Salvoes from an artillery salute shook the crowds that gathered along Phnom Penh's Tonle Sap River as the embalmed body of the former monarch, who died aged 89 of heart failure on 15 October, was cremated in a gold casket by the Royal Palace.

Sihanouk helped win independence from French colonial rulers, but was later unable to stop his country being dragged into the Vietnam War despite his political wheeling and dealing that critics say precipitated a slide into chaos and the Khmer Rouge "Killing Fields" revolution.

He abdicated in 1955, ostensibly to strengthen his political influence and became increasingly authoritarian to preserve that power.

After his ousting in a US-backed coup in 1970, Sihanouk made an ill-fated pact with Pol Pot's Khmer Rouge, becoming a prisoner in his palace and losing five children and 14 grandchildren during the group's 1975-1979 ultra-Maoist rule.

As peace returned to Cambodia following a UN-brokered shift to a fragile democracy, Sihanouk retook the throne in 1993, but discovered his power and influence had waned significantly.

After 11 years, he abdicated again and lived for much of his time in China, where he spent his last days.