Bomb hoax sees SA racecourse evacuated

South Australia's Morphettville racecourse has been evacuated briefly over a bomb threat.

Crowds in a section of the racecourse were ushered away briefly on Saturday afternoon after the racecourse received a threat, SA police say.

"Someone rang the racecourse, they did a bit of a search and evacuated a small part of the area but nothing has been located," a police spokesman told AAP.

Punters have been allowed to re-enter the racecourse and the races have resumed.

A spokeswoman for the racecourse said police and emergency services were notified immediately after receiving the threatening call.

The call was allegedly made via a public payphone, announcing there was a bomb threat in the grandstand.

Police helped monitor the situation as racecourse officials searched the area.

There was a one hour delay for punters, with social media photos showing crowds gathered outside the grandstand area waiting for the threat to pass.

The elderly and those at risk were ushered into air-conditioned rooms to wait.