"Sri Lanka Shipping Co. was contracted to tow the rig 'Transocean Nordic'. Towage has been undertaken by the tug Mahanuwara," the company said.
The rig is presently being towed by Mahanuwara at a speed of 3-3.5 knots.
Sri Lanka Shipping said it would take about three weeks to complete the tow on the 1,919 nautical mile voyage.
Sri Lanka Shipping's other tug, Maha Oya, is employed in towing rigs in the Middle East, a new market for its towage services.
Maha Oya operates from the port of Sharjah and provides support tug services in moving rigs in the Persian Gulf.
Sri Lanka Shipping also provides ship agency services and supplies bunkers in Colombo port. .