The new office in Galle is located near a new expressway connecting the southern port town with Colombo, which has sharply reduced transit time between the harbour and the island;s international airport.
"The strategic location of Galle port at the southern tip of the country offers an excellent base for offshore ship supply services," said Preethilal Fernando, chief executive of GAC Sri Lanka.
"Demand for such services is set to grow as the government opens up more areas for oil and gas exploration."
Cairn India has struck oil and gas in the northwestern Mannar Basin and GAC is providing support services for the exploration programme.
GAC Sri Lanka provides ship agency services including crew transfers and supplying food and other provisions as well as spares for ships passing Galle which is close to the main East-West shipping route across the Indian Ocean.
It also handles all types of port calls and provides logistics services for infrastructure projects needing movement of heavy cargo.
GAC said in its statement that the new office in Galle, located near the island's first expressway connecting Galle and Colombo, has helped to reduce the transfer time between the port and Colombo airport by more than three hours.
"Its close proximity to the local authorities also helps reduce clearance times."
The operations are supported by GAC's own fleet of vehicles and a fleet of launches, which operates round-the-clock to manage crew changes, deliver spares, provisions and mail, and to respond to emergency situations, GAC said.
The company has also opened a new branch in the new port in southern Hambantota, further south of Galle, to cater to increased maritime activities.
"Hambantota encompasses shipbuilding, ship repair, warehousing and bunkering facilities," the statement said.
"Its location on the south-east of the island makes it an ideal option for ships plying the busy international shipping lanes to and from the Far East.