Calls for a windfall tax on oil companies have been reignited after Royal Dutch Shell posted record UK company profits of almost £14 billion.

The Unite union said profits in the industry were "obscene" and urged the Government to take action, especially because of rising energy prices.

Royal Dutch Shell reported a surplus of 27.6 billion US dollars (£13.9bn) in 2007, equivalent to £1.5 million an hour and 9% higher than a year ago.

It benefited from rising crude oil prices of more than 90 US dollars, a factor which also left motorists with average petrol costs of more than £1 a litre.

Unite joint general secretary Tony Woodley said: "Shell shareholders are doing very nicely whilst the rest of us, the stakeholders, are paying the price and struggling.

He added: "This Government took the brave step of putting a windfall tax on the greedy privatised utilities to fund the New Deal. With pensions injustices still to be addressed, fortune should favour the brave again and the greedy oil companies should be asked to contribute for the common good."

Shell rejected the windfall tax calls, arguing that the profits figure is almost matched by the amount of money it spends on securing new energy sources. Most of its haul comes from exploration and production, rather than UK forecourts.

Chief executive Jeroen van der Veer said: "If you get additional taxation, in the end it means you can invest less. The money has to come from somewhere and over time it will impact on our production."

The oil firms, including Shell, insist they already pay high levels of tax to the Treasury. In 2005, Chancellor Gordon Brown increased a North Sea tax on energy companies from the 10% he introduced in 2002 to 20%.

Independent charity the RAC Foundation said anger over rising petrol costs needed to be directed towards the Government, adding that a flexible fuel duty would compensate for varying crude prices.