British Gas parent Centrica has announced a £2 billion deal with Qatar for the supply of enough gas to meet the needs of around 2.5 million UK households.
The three-year supply contract for liquefied natural gas (LNG) with Qatargas is the first deal of its kind for the UK firm.
Centrica added the agreement was an important step forward in meeting the UK's energy needs as competition for gas increases and North Sea production declines.
The deal, which was unveiled as chief executive Sam Laidlaw accompanied Prime Minister David Cameron on a trade delegation to Qatar, will provide enough gas to meet around 10% of UK residential gas demand and around 25% of households supplied by British Gas.
Mr Laidlaw said: "The UK is the largest gas consumer in Europe and one of the fastest growing markets for gas imports.
"LNG provides the UK with a bridge to major global gas reserves. This deal is of particular importance and we hope that this will be the start of a longer term working relationship.
"The relationship between Qatar, the world's leading LNG exporter, and the UK connects supplier and consumer nations.
"Securing gas supplies benefits our customers, underpins our business and provides an important component of the UK's long term energy security."
Mr Cameron welcomed the deal, adding: "This important agreement is good for Britain, good for our energy security, good for jobs, and good for economic growth."
