Man pulls gun in footy field robbery

A man has had a gun pulled on him as he tried to intervene in a robbery at a touch football ground in Campbelltown, in Sydney's west.

The incident occurred on Monday night when the alleged assailant - dressed in all black and wearing a balaclava - was spotted rifling through and stealing a bag containing cash, an iPhone and wallet.

When the man challenged him it is alleged the thief produced a pistol before fleeing to a waiting silver Toyota Kluger parked near Stromeferry Reserve.