Sri Lanka Monday unveiled a 1.2-billion-dollar plan to expand the island's main sea port to triple its container handling capacity, the Sri Lanka Ports Authority said.

The port of Colombo will add four terminals, each with four berths, under the project launched by President Mahinda Rajapakse.

Construction work is expected to begin in July next year and be completed within 39 months, the state-owned company said.

It said the current capacity of four million containers a year will be raised to 12 million once the work is completed.

The estimated cost for the expansion is 1.2 billion dollars, but the port authority did not give funding details.

"This project, which will result in the creation of a government-built and owned harbour facility, will include public-private partnerships in the provision of terminal services," the authority said.