Detectives investigating a string of ATM explosions have arrested two men at gunpoint in Sydney's south-west overnight.

In the past six months there have been dozens of ATM blasts, mainly across Sydney, but also on the New South Wales central coast and one at Warrawong on the south coast.

Strike Force Piccadilly II has been under growing pressure to make a breakthrough on the case, with only three people arrested so far.

About 3:30am (AEDT), police from the Tactical Operations Unit arrested two men - one 23 years old, the other 25 - outside a bank on The Boulevard at Punchbowl.

Police seized a BMW sedan, which they suspect is stolen, and say they found gas cylinders in the car.

The men were questioned at Campsie Police Station, and police say they have now been charged.

Police expect both men to face Burwood Local Court later today.

They have asked anyone with information that might assist detectives with their ongoing inquiries into the ATM explosions to contact Strike Force Piccadilly II via Crime Stoppers on 1800 333 000.