The news that Norway's national oil company is to shut a major gas pipeline for at least six months could prompt electricity and gas bills across the UK to rise significantly, market observers have warned.

While StatoilHydro has stated that it intends to repair the leak discovered in its pipeline bringing gas onshore from its Kvitebjorn field as soon as possible, it confirmed that operations are likely to recommence in spring 2009 at the earliest.

Given that the field was expected to produce up to 7.4 billion cubic metres of gas over the course of 2008, with much of this to be made available in the UK, the development looks set to push wholesale prices higher still.

Patrick Heren of consultancy firm ICIS Heren, told the Financial Times: "Relative to peak UK supply, the amount of gas affected is a relatively small proportion. But at the margin, when supply is tight over the winter, if you take a small amount out of the market that is going to have a severe effect on prices."

This comes as four of the six major UK gas suppliers are expected to announce a fresh rise in their tariffs, with EDF and British Gas owner Centrica having increased their rates last month.