DUBAI, March 14 (Reuters) - State-owned Qatargas said on Tuesday it had agreed to increase the volume of liquefied natural gas which it supplies to Polish Oil and Gas Co to 2 million tonnes per year.

The new deal will come into effect at the start of 2018 and run until June 2034, it said. Poland has been trying to diversify away from its reliance on Russian pipeline gas.

The LNG will be supplied from Qatar Liquefied Gas Co, a joint venture between Qatar Petroleum, ConocoPhillips and Mitsui & Co 8031.T , and will be delivered by Q-Flex LNG vessels to the President Lech Kaczynski LNG Terminal in Swinoujscie, Poland.

A long-term deal signed in 2009 provided for Poland to import 1.3 billion cubic metres of LNG from Qatar annually, and those deliveries began last June.

(Reporting by Andrew Torchia) ((andrew.torchia@thomsonreuters.com; +9715 6681 7277; Reuters Messaging: andrew.torchia.thomsonreuters.com@reuters.net))