Police are investigating an aggravated robbery at Coles Paralowie this morning.

At about 6.30am a man entered the Libererator Drive store armed with a knife threatened a staff member and demanded money.

He left with a sum of cash and was last seen running towards Ronaldo Way.

The man was wearing all dark clothing and a white baseball cap.  He was carrying a red shopping bag with yellow writing.

He is described as Caucasian, with fair skin and freckles across his nose.  He is about 170cm tall, slim build and has a reddish goatee.

There were no injuries.

Anyone with information about this robbery is asked to contact BankSA Crime Stoppers on 1800 333 000 or online at www.sa.crimestoppers.com.au.