Police have arrested a man in relation to three alleged armed robberies across Sydney yesterday.

About 6.20am (Sunday 27 October 2013), a man entered a service station on Parramatta Road at Granville and allegedly threatened a staff member with a knife.

The man fled the location in a vehicle a short time later with cash and cigarettes. No one was injured during the incident.

Officers attached to Rosehill Local Area Command attended and launched an investigation.

A crime scene was established at the location and examined by specialist forensic officers and detectives.

Just before 10am, a console operator was allegedly threatened by a man with a screwdriver at a service station on the Hume Highway in Lansvale.

The man demanded cash and cigarettes before driving away from the location.

Police from Cabramatta Local Area Command attended and established a crime scene, which was later examined by forensic specialists. No one was injured during the alleged robbery.

During the early afternoon, the armed man also allegedly threatened another staff member at an Ermington service station on Victoria Road.

The staff member was not injured and the man fled the location in a vehicle, with cash and cigarettes.

Rosehill police were alerted and attended the location, where they established a crime scene.

Following inquiries, police arrested a 22-year-old Merrylands man in a vehicle on Good Street at Granville, about 10.30pm last night (Sunday 27 October 2013).

The man was taken to Parramatta Police Station, where he is currently assisting detectives with their inquiries.

While investigations into the incidents are continuing, police expect a number of charged to be laid.