Qatargas on Wednesday signed a deal to export an additional 200,000 tonnes per annum of liquefied natural gas (LNG) to Japan's Chubu Electric Power Company and Shizuoka gas Company.

The six-year agreement signed on the sidelines of the World Petroleum Congress in Doha stipulates that Qatargas will start delivering the LNG in 2016 from the Qatargas 1 joint venture.

The deal "further nurtures our long-lasting relationship with Chubu Electric Power Company while it welcomes Shizuoka Gas Company as the first new long-term Japanese buyer of LNG," said Qatargas CEO Khalid bin Khalifa al-Thani.

Demand for gas has increased markedly in Japan, the world's largest importer of LNG, since a massive tsunami in March placed the country's nuclear energy supply under pressure.

Qatargas has sold LNG in excess of a total of seven million tonnes annually to Japan. In the aftermath of tsunami, Qatargas increased its sales commitment to Japan to nine million tonnes, according to a statement.

The small Gulf emirate, which holds the world's third-largest gas reserves, last year celebrated raising its LNG production capacity to 77 million tonnes annually, boosting its position as the world's largest producer.