The Australian man accused of a fatal assault against a Cork man in Perth has had his charge upgraded to murder.

Charles McCarthy was allegedly struck on the head with an object as he was out walking with his wife and a friend in the early hours of Saturday 23 December.

He was taken to hospital but later died from his injuries.

Andrew Doan, 34, was last week charged with causing grievous bodily harm to the 32-year-old.

The charge was upgraded to murder during an appearance in Magistrates Court of Western Australia this morning, according to local news reports.

Mr Doan was not required to enter a plea to the charge and spoke only to confirm his name and that he understood the charge.

His lawyer made a bail application last week following the initial charge, arguing that Mr McCarthy charged at Mr Doan before the fatal blow.

He told the court that Mr Doan's actions were more like self-defence than murder.

The bail application did not proceed after the charge was upgraded to murder.

It is understood Mr McCarthy, who was from Upper Aghada in Co Cork, moved to Australia in 2000. He worked as a cable layer in Perth and is survived by his wife and two young children.