A 31-year-old Curtin man is accused of robbing the Old Canberra Inn of cash early on Sunday morning.

Police say the man had been drinking at the pub on Mouat Street, Lyneham, before leaving the location at about 10.30pm.

They allege the man returned to the pub at about 12.15am on Sunday, produced a knife, demanded money and threatened staff. He  fled with cash.

CCTV footage showed the alleged offender was wearing the same clothes as when he was at the pub earlier on Saturday evening. Pub staff were also able to identify the man.

Late on Sunday night police arrested the man at a Curtin home and charged him with aggravated robbery (offensive weapon) and aggravated burglary (intent to commit theft).