Households in Scotland would have to pay £875 a year more in energy bills under independence, Labour has claimed.

Jackie Baillie said the loss of UK renewables subsidies would lead to a price hike for consumers north of the border.

She made the claim as she hit out the First Minister for failing to support Labour plans to freeze energy prices if it wins the next UK general election.

Ms Baillie pressed Alex Salmond on the issue when she stood in for Johann Lamont at First Minister's Questions at Holyrood, as the Scottish Labour leader was attending the funeral of party veteran Tony Benn in London.

Mr Salmond highlighted SNP plans to cut fuel bills for consumers in an independent Scotland - which he insisted where better than Labour's proposals for a price freeze.

If the Nationalists are in power in an independent Scotland, they would remove levies for tackling fuel poverty and improving energy efficiency from bills, with these instead being paid directly by the Government.

This could cut energy bills for people in Scotland by 5%, or £70 a year, according to the SNP.

But Ms Baillie claimed fuel bills would increase if there was a Yes vote in September.

She said: "We operate in the UK energy market, we get a third of the overall UK budget for renewables, despite our population being one tenth.

"Independence would remove that. Independence would cost an extra £875 per year for each household to make up the renewables shortfall, that's the price of independence on families already struggling to pay their bills."

Mr Salmond said: "The SNP proposed a £70 cut for family energy bills, which by definition is rather better than freezing energy bills."

He also warned if Labour continued to support nuclear power, that would result in energy bills "going upwards".

The First Minister was pressed on the issue the day after power firm SSE announced it is to freeze household gas and electricity prices until January 2016.

Today, the regulator Ofgem revealed the Big Six energy suppliers are to face a full-scale competition investigation, claiming profits in the sector had quadrupled in the last three years.

Ofgem said a probe by the Competition and Markets Authority would ''consider once and for all whether there are further barriers to effective competition''.

But Ms Baillie claimed "From the beginning of this debate the First Minister has been on the side of the energy companies rather than on the side of ordinary Scots struggling to pay their bills."

She said the First Minister had "stood shoulder to shoulder with David Cameron" in opposing a price freeze.

"As SSE freeze prices and Ofgem announce they will reform the market, surely the First Minister, even he, has the humility to admit Labour was right and he was wrong," she said.

"Now Labour's policy has been adopted by one of our major energy companies, now that Ofgem are following Labour's lead, will the First Minister finally admit he was wrong and has let down families struggling with gas and electricity bills? Or is sorry simply the First Minister's hardest word?"

Mr Salmond said: "Jackie Baillie omitted to mention in her declaration of 'we was right' that the SNP proposed a £70 cut for family energy bills, which by definition is rather better than freezing energy bills."

He welcomed Ofgem's announcement, saying such an investigation was "a far more sustainable way to look at these matters and ensure that families are protected".

But he said the review should look at the issue of nuclear power, and the UK's support for the Hinkley Point station in Somerset - saying the contract there had been set at twice the wholesale price for electricity.

The First Minister said: "The review in competition in the energy markets is welcome, that offers the opportunity to fully examine the market place and I hope and believe the Labour Party will see the sense in extending that review to nuclear power and the contract that has been offered to Hinkley Point.

"For the very obvious reason that if you continue your support for that contract, a contract at double the wholesale price for electricity, there would only be one direction for electricity bills in the future, and that is upwards."

He added: "Let's have a review and a competition examination, examining the conduct of the big six energy companies and also the huge nuclear subsidy."

The SNP leader also hit back at the claims he had "stood shoulder to shoulder" with Mr Cameron.

He told Ms Baillie that by being part of the Better Together campaign, Labour was "not just shoulder to shoulder but hand in glove, umbilically linked to the Conservative Party".

He claimed that meant Labour had become "an extension of the Conservative Party".

Mr Salmond insisted: "£70 off household bills may be irrelevant to Jackie Baillie and to the Labour Party, it will be greatly welcomed by families in Scotland as a substantial proposal."

He also stated that SSE had said Labour's proposed price freeze "would not significantly reduce energy prices or provide energy investors with the long term quality they require to invest in the energy infrastructure that consumers depend on".