CCTV shows men try to rob Sydney Macca's

Terrifying footage has emerged of two men trying to rob a McDonald's with a sawn-off shot gun in Sydney's southwest, as police continue their hunt for the pair.

Video footage released by police on Friday shows the men knocking on the drive-through window at the Prestons fast-food restaurant before pulling out the shotgun and threatening the 18-year-old woman who was at the drive-through window on August 16.

The men fled on foot empty handed but were again captured on camera robbing a man at a nearby Liverpool newsagency the following day, Detective Inspector Dean Johnstone told reporters on Friday.

Clear vision has captured one offender's face, his features contorted in rage as he appears to threaten the man behind the counter, and police are hopeful the public may help to identify him.