Media playback is unsupported on your device Media caption Mr Miliband said energy companies could "stomach" plans to freeze bills

Labour leader Ed Miliband has said he is "absolutely clear" that energy bills will be frozen if his party wins the next general election. 

"We are absolutely confident because we've done all the figures, we've looked at all of the issues," he told the BBC's Breakfast programme. 

He repeated his accusation that energy companies have been over-charging businesses and consumers. 

Critics have warned that the plan could put future energy supplies at risk. 

But Mr Miliband claimed that energy companies were "unreliable witnesses" in the debate: "They're the people who would say that anyway." 

'Illegal'

"There's a cost-of-living crisis in this country.  Energy bills are a big part of it," he said. 

"For too long the companies have been able to over-charge people.  Somebody's got to stand up and be counted. 

We're absolutely confident the companies can stomach this, can make this happen, and we're going to make this happen Ed Miliband, Labour leader

"That's why we'll freeze energy bills until the beginning of 2017 if we win the election.  That will benefit 1.5 million businesses across our country, make a big difference to them." 

The policy was unveiled at the party's annual conference last week, and has faced strong criticism about its feasibility and the effect it would have on investment in energy infrastructure. 

But Mr Miliband continued: "Even if wholesale prices rise, this freeze is going to happen.  I want to be absolutely clear about this. 

"We're absolutely confident the companies can stomach this, can make this happen, and we're going to make this happen." 

He again dismissed predictions that energy companies might try to "collude" and hike prices before the election. 

"If they try and do that, that is illegal," he said, "they can't do that." 

'Blackouts'

Labour has also released figures suggesting that British business could save £1.5bn if the price freeze came into force. 

The party said the estimate was based on research by the House of Commons Library. 

Meanwhile, two energy companies, EDF and First Utility, have unveiled plans to freeze current prices voluntarily. 

EDF Energy unveiled a new tariff that fixes bills until 2017, and First Utility said its current variable tariff would be frozen until March 2014. 

The former head of the UK's competition watchdog, John Fingleton, has suggested Labour's price-freeze policy was unlikely to work. 

"In the long term [it] will harm consumers, and taking political responsibility for prices you cannot ultimately control is quite risky," he said earlier this month. 

The Conservatives have accused Labour of "bashing business" and insisted action was already being taken to ensure customers are on the cheapest tariff. 

Energy UK, the trade body representing the six largest energy firms, said the move could push up prices across the board and threaten the 600,000 people employed in the industry.