The first gas from a new Dutch pipeline which ends in Norfolk has begun flowing under the North Sea.
Gas pipeline being laid across the North Sea to the Netherlands
The development will supply 8% of the UK's gas needs, and the government said it will increase energy security and add downward pressure to power prices.
The new 235km (146 miles) pipeline runs from the Dutch continental shelf to Bacton in Norfolk.
Trade and Industry Secretary Alistair Darling said the project was "a feat of considerable engineering achievement".
The construction of the pipeline followed a treaty signed by the UK and Dutch governments in 2005.
Mr Darling said: "A further step to secure Britain's energy supplies is put in place today."
Lord Truscott, Parliamentary Under Secretary was in Bacton to mark the opening of the pipeline.