Taiwan's state oil supplier said Hiesday it has signed a 20-year contract with Papua New Guinea to import liquefied natural gas as the island seeks to diversify overseas energy sources.

CPC Corporation Taiwan said that under the agreement it will import 1.2 million metric tonnes of LNG from US energy giant ExxonMobil's Papua New Guinea project each year beginning from December 2013.

The deal, resulting from two years of talks, follows "the government's policy of expanding the use of liquefied natural gas," CPC said in a statement.

It would begin "a new and lasting relationship between Taiwan's largest energy importer and PNG's first LNG project," said ExxonMobil Gas and Power marketing's vice president for LNG, Ron Billings.

Billings said the deal was a significant step for the 15 billion US dollar PNG project, which is tapping into huge Asian demand for cleaner-burning fuels, with all of its production capacity now committed on a long-term basis.