A 41-year-old man has been arrested for allegedly killing his father after a heated quarrel in their Bedok North flat last Friday.

The man, Tan Kok Meng, works as a taxi driver and is believed to be mentally challenged, The Sunday Times understands.

He is expected to be charged today with murder. If convicted, he faces the death penalty.

Neighbours told reporters that they heard a loud argument in Mandarin coming from the flat on Friday evening.

Mr Muhd Zin, a supervisor who lives on the same floor, had investigated, along with his 18-year-old son, after he heard the shouts.

They found Tan's 75-year-old father lying in a pool of blood in the living room. "I was stunned when I saw the blood," Mr Zin, 55, told The New Paper.

Other neighbours told reporters that the dead man's wife worked as a cleaner and the couple were very loving.

A relative, who wanted to be known only as Mr Toh, told Chinese evening newspaper Shin Min Daily News that the father and son did not have a good relationship.

Mr Toh, a 64-year-old businessman, said he rushed to the flat after getting a call from the senior Mr Tan's wife following the incident.

"When I got here, (Mr Tan) had already been taken away by paramedics," he said.

A police spokesman said they received a call about the incident at 5.21pm on Friday. Officers had found the elderly man lying motionless in his home with head injuries when they arrived.

He was rushed to Changi General Hospital and was pronounced dead at 6.37pm.