Labour to make North Sea gas field decision 'imminently' as winter energy fears mount

But she told the Energy UK conference in central London that a decision on Rosebank, Britain’s largest untapped oil field, will take longer.

Work at both fields has been in limbo after legal challenges were made on climate grounds.

Decisions on the future of both rest with Ms Fahnbulleh.

Prime Minister Andy Burnham has pledged a "pragmatic" approach.

Industry leaders have said that Jackdaw could be supplying British homes with gas this winter.

Approving both fields, they say, would benefit the economy, the climate and the UK’s energy security.

But climate campaigners are fiercely opposed to the projects.

Foreign Secretary Ed Miliband once referred to Rosebank as "climate vandalism".

It had been widely predicted that an announcement would be made last month, leading to claims that it had been delayed until after the Holborn and St Pancras by-election, in which Green Party leader Zack Polanski stood unsuccessfully.

Labour denied this, claiming that there was simply a huge amount of documentation to deal with.

However, the Government had previously refused to be drawn on when a decision would be announced.

Ms Fahnbulleh, a keynote speaker for the conference, held by the trade body for the energy sector, was asked if decisions had been made on either field.

She replied: "As you will understand, we are in a quasi-judicial process, and I won't get into the specifics. What I will say is we have got all the information on Jackdaw, and the department has gone through that and so there is a decision that will be imminent.

"Rosebank will take a little bit longer. But because my first two months of the job have been completely dominated and inundated with this question, when I have got a 100,000 things in my in-tray, I have an incentive to make sure that we come to decisions as quickly as we can."

Shadow Energy Secretary Andrew Bowie spoke earlier at the same event and questioned why no decisions had been made on the North Sea projects.

He pointed out that the Government had just given the green light to a huge oil field off the Falkland Islands.

Mr Bowie said there was a "supreme irony" in the fact Mr Miliband was the one to sign off the Falkland field when, as energy secretary, he had not approved Rosebank or Jackdaw.

He went on: "It really does beg your question - why is it okay to drill for oil and gas in the South Atlantic, but not in the North Sea? Why is it okay for the Government to sign off on jobs being created in oil gas in Port Stanley, but not in Aberdeen?

"You can’t claim that the government's policies on the North Sea are about successful climate leadership, yet our own overseas territories aren't following them."