HONG KONG: The severed heads of a Hong Kong couple were found in a refrigerator at a bloodstained apartment in a gruesome murder for which their 29-year-old son has been arrested, according to reports.

Police said in a statement Friday that "some sections of human body" had been found at a flat in Tai Kok Tsui on the outskirts of the city and that they suspected the victims were a 64-year-old man and his wife.

They had been reported missing last Saturday, police said.

The couple were identified as Chau Wing-ki, 64, and his wife Siu Yuet-yee, 63, by Hong Kong newspaper the South China Morning Post (SCMP).

Their heads had been found in the refrigerator and parts of their arms and legs were also discovered in the flat, according to the SCMP, while their bodies remain missing.

Police also found saws, knives and a chopping board in the flat along with plastic moisture-proof boxes and bags containing body parts, the SCMP reported.

The couple's 29-year-old son, and a 35-year-old man were arrested on suspicion of the murders, which police say occurred on March 1.

The arrests led police to the building where the victims' body parts were found, detective superintendent Angus Pullinger told reporters, adding they discovered items "which would suggest that some cutting took place".

"We have reason to believe the flat was the site of the killing," senior superintendent Eddie Ma told the SCMP. "We are now investigating the motive," he said.

Ma also said that one of the suspects had confessed to murdering and dismembering the couple at the flat.

Police were not immediately available for further comment when contacted by AFP.

The couple was reported missing by their eldest son last Saturday, according to the SCMP, but the 29-year-old son told police he saw his parents on March 2 and that they told him they were travelling to mainland China.

Police became suspicious after they failed to find record of the couple leaving the city, the newspaper said.