One of the biggest continental suppliers of gas and electricity to the UK, GDF Suez, today highlighted how foreign operators were making massive profits thanks to the energy price boom with profits rocketing 14% to ¤3.38 billion (£2.7 billion) in the first half of the year.

Sales in the period shot up 17% to ¤43 billion with the company citing: “growing energy sales in Europe and internationally against a background of high market prices and a well-balanced and developing power-generation base”.

News of the profits will add to calls for a windfall tax on energy companies.

In the UK, GDF Suez is one of the bigger players in exploration and production with its GDF Britain division while its GDF ESS operation supplies industrial and other commercial clients with gas and electricity.

Energy costs to manufacturers and other businesses are cited as one of the main causes of the current high inflation rate.

GDF recently upped its operations in the UK with the acquisition of the Teesside power plant.

It also last year made a move into the UK's underdeveloped gas storage business with the acquisition of a vast salt cavern from the Ineos group.

In its home country of France, GDF, along with other energy companies, has its profits capped by tough regulatory controls of charges for household power. French gas and electricity bills are among the cheapest in Europe. Last month, the regulator allowed it to increase power charges by 2%.

The UK Government has faced increasing calls for a windfall tax on energy companies who have all been making massively increased profits as household bills have rocketed. They argue that their profits are being made from other parts of their businesses, rather than from the consumer price rises.

It is not clear yet whether commercial-only suppliers like GDF Suez could get caught up in any one-off tax on gas companies.

Today's results are the first since the merger of Gaz de France and Suez last month.