A police officer has been fined $500 for leaving his four-year-old daughter locked in a car in full sun while he was in a pub.

The hot and distressed child was found by passers-by clinging to a partially opened window just after midday on March 28 - 45 minutes after her 35-year-old off-duty father had entered a bar at Bankstown.

On Wednesday, he was fined $500 by Magistrate Richard Miszalski in Bankstown Local Court after pleading guilty to a charge of leaving a child in a motor vehicle and causing emotional distress.

The officer, who cannot be named, was also ordered to pay court costs of $83.

NSW police Assistant Commissioner Mark Murdoch on Wednesday told reporters he was disappointed by the officer's conduct.

"It's less than encouraging and pretty ordinary actually that we have a police officer engage in that sort of behaviour."

His duty status was under review shortly after the incident.

But Mr Murdoch said it was up to the officer's commander to determine if further disciplinary measures were appropriate and refused to comment further.