Hong Kong police have arrested three men after discovering around 69kg of suspected cocaine worth HK$42 million, with traffickers believed to have hired divers to retrieve the drugs from near-shore waters, a tactic encountered by officers for the first time.

A police spokesman said on Sunday that officers had conducted an anti-drug operation in Tsing Yi near Stonecutters Bridge the previous day and spotted three men loading three large bags into a suspicious private car.

They stopped the trio for an inspection and found three large packages in the car while the suspects attempted to resist arrest.

A search of the vehicle uncovered 69 bricks of suspected cocaine, each weighing about 1kg.

Police also discovered diving equipment, including a wet suit, flippers, an oxygen tank and an underwater scooter, near the shore.

The force said it was believed the drugs were illegally transported to Hong Kong and left in near-shore waters, with a syndicate arranging for divers to retrieve the packages before trafficking.