People from all walks of life expressed deep sorrows Monday over the death of the most revered Former King Norodom Sihanouk, 90, from natural causes.

Sihanouk died at 1:20 am early Monday (local time in Phnom Penh) due to natural causes in China's Beijing Hospital, said a government statement announced by the state-owned National Television of Cambodia Monday.

Phay Siphan, spokesman for the Council of Ministers, said that Cambodia saw the King Father as a great Cambodian hero who brought Cambodia full independence, peace, national reconciliation and unity.

"The former king was the father of independence, territorial integrity, and national reconciliation and unity," he told Xinhua over telephone.

Government spokesman and information minister Khieu Kanharith said, "Former King was the symbol of the national heroes and he was the founder of diplomatic relations between Cambodia and China and the ties have been steadily strengthened and fostered until today."

Sihanouk suffered from various forms of cancer, diabetes and hypertension and had been treated by Chinese doctors in Beijing for years before his death.

"Cambodia would like to express sincere and heartfelt gratitude to the Government of China, Chinese people and doctors for supporting and treating the King-Father for years," Phay Siphan said.

Born on Oct. 31, 1922, Norodom Sihanouk reigned Cambodia from 1941 to 1955 and again from 1993 until his voluntary abdication on Oct. 7, 2004 in favor of his son, the current King Norodom Sihamoni.

On Monday morning, state flags are flying at half-mast across the country to mourn the death of the King-Father, whilst Cambodian King Norodom Sihamoni and Prime Minister Hun Sen left the country for Beijing in order to bring home the King-Father's body for a traditional funeral at the Royal Palace.

Sihanouk wrote in a royal letter in January, 2012 that he requested his body to be cremated instead of being buried and his ashes to be put in an urn, preferably made of gold, and placed in a stupa at the country's Royal Palace.

Prince Sisowath Sirirath said Monday that the departure of the King-Father was a great loss for royal families and Cambodian people as a whole.

"He left us with good memory and great achievements for the nation," he said.

Cambodian Deputy Prime Minister Nhik Bun Chhay said, "This is a great loss for Cambodia. We feel very sad. The former king was a great king that we all respect and love him."

On Monday, the National Television of Cambodia has repeatedly screened a 30-minute compiled documentary on Former King Norodom Sihanouk's royal crusades in rehabilitating and constructing the nation since his first coronation in 1941.

The film features the Former King's activities in commanding armed forces, struggling for the nation's independence, developing the nation in all fields and devoting to humanitarian activities.