An investigation is underway after an Ermington service station was robbed by a man armed with a knife this morning.

Police from Rosehill Local Area Command were called to the business on Victoria Road about 12.48am (Friday 6 February 2015), following the robbery.

Police were told a man entered the business and threatened the attendant with knife, demanding cash. He was handed cash and ran from the scene.

A dog squad was called to assist with the search for the man but he has not yet been found.

Police now want to speak with a man they believe can assist with their investigation.

He is described as being of Caucasian appearance, aged in his 20s, with a thin build and about 175cm-180cm tall.

At the time he was wearing a navy blue cap and dark clothing