Trio arrested after NSW hold-ups

Three people have been arrested over a string of armed robberies at petrol stations across Sydney's southwest.

A woman, 21, and two men aged 18 and 20 allegedly held-up three service stations in Villawood, Cabramatta West and Lansvale early on Wednesday morning while armed with knives and a metal pipe, demanding cash and cigarettes from the attendants.

Police also found a submerged car at the end of a boat ramp in Lansvale which they believe is linked to the robberies.

The trio was arrested when their taxi was pulled over a short time later; a search of the group uncovered items which police believe may have been stolen.