Marine police launches and a Government Flying Service helicopter were scrambled yesterday afternoon after mainlanders boarded a Panamanian-registered vessel as it left Hong Kong waters.

The captain of the 2,000-tonne Xiamen Bridge radioed a distress signal to the Marine Department saying his vessel had been stopped and boarded by 'persons unknown' near Waglan Island at 1.30 pm.

A helicopter and two high-speed launches were dispatched by the Marine Police base, but by the time they had arrived the ship and the mainland vessel were in Chinese waters.