Centrica has signed a 4.4 billion pound ($7 billion), 4-1/2-year deal with Qatar to import liquefied natural gas (LNG) supplies as domestic production dwindles, the British utility said on Wednesday.

Centrica is to buy 3 million tonnes of LNG per year, or the equivalent of approximately 13 percent of Britain's annual residential gas demand, it said.

The deal extends a 2 billion pound, three-year LNG supply agreement between Centrica and Qatar, the world's biggest producer of shipped gas, it signed in 2011 and which expires in June 2014.

"It is vital that the UK has a diverse range of sources of supply to meet its energy requirements," Chief Executive Sam Laidlaw said.

Britain, which became a net gas importer for the first time in 2004, depends on gas via pipelines from Norway, its biggest supplier, and from mainland Europe countries such as the Netherlands and Belgium.

The country's North Sea reserves saw a peak in output at the turn of the century and have seen sharp declines ever since, boosting dependence on LNG suppliers such as Qatar.

"Long term deals of this kind with reliable suppliers like Qatar are vital for our future energy security," UK Energy Minister Michael Fallon said.

So far this year, 93 percent of Britain's LNG imports have come from Qatar. Qatari gas has so far this year made up 19 percent of Britain's total gas imports.

The volume of Qatari LNG arrivals in Britain has slowed down, with 38 percent fewer cargoes arriving in Britain so far this year compared with the same period last year.

High demand in Asia has meant that Qatar diverts more of its supply to the highest-paying market, and away from Europe. – Reuters