A US talk show host casually suggested ‘involuntary lethal injection’ for violent homeless people with mental health problems who refuse Government assistence.

He apologised four days later, describing his comments as “extremely callous”.

The remark was made by one of the hosts on a daytime talk show as they discussed the violent stabbing of a young woman on a metro train by a repeat offender who authorities described as mentally ill and homeless.

One host said the average citizen “shouldn’t have to live in fear” of being attacked on buses, trains or on the streets, and added that “billions” had been spent on “mental health and the homeless population” but that many had refused that help.

He added that they should not be given a choice, either they take the resources on offer or be locked up in jail.

To which his cohost replied, “Or involuntary lethal injection or something. Just kill ’em.”

He quickly moved on to say voters needed politicians who would be “tough on crime” without any protest from the other two hosts.

Four days after his comments went viral he issued an apology.