The alleged killer of right-wing activist Charlie Kirk appeared to take responsibility for the shooting on the messaging platform Discord, a company spokesperson has confirmed to CBS, the BBC's US partner.

According to the spokesperson, Tyler Robinson, 22, messaged friends in a chat on Discord hours before he was arrested last week in connection with Kirk's shooting at an event at Utah Valley University.

"It was me at UVU yesterday. im sorry for all of this," reads a message from an account that allegedly belongs to Mr Robinson, according to the spokesperson and a law enforcement source.

Mr Robinson, who has not yet been formally charged, is due to appear in court on Tuesday.

Arrested on suspicion of aggravated murder, felony discharge of a firearm and obstruction of justice, he could face the death penalty.