Britain's main power link to France was partially severed during Storm Angus and will not be fixed until February, National Grid has revealed, exacerbating fears of a power crunch this winter.

The Interconnexion France-Angleterre (IFA) link between Folkestone and Calais is Britain's biggest interconnector, allowing it to import up to 2 gigawatts of power from the continent to help keep the lights on when UK supplies run low.

A fault developed on the interconnector on the morning of Sunday November 20th, as Storm Angus battered the UK.

National Grid, which is the joint owner of the link, said it had now discovered that four of its eight cables "have been severed", putting 1GW of capacity out of action until the end of February.

The unprecedented damage - which it is thought could have been caused by a ship dropping anchor during the storm - comes as Britain heads into winter with power supplies already tight and National Grid expecting to have to draw on emergency back-up power plant reserves to keep the lights on.

Analysts at Barclays said the outage was "likely to lead to increased volatility and higher UK power prices over January and February 2017 – especially during peak demand periods".

A report by ENTSOE, the trade body for European power system operators, published earlier on Tuesday warned that "the UK will need high imports from all neighbouring countries" this winter, though it acknowledged the existence of back-up plans.