The electricity price cut from British Gas sets the tone for tariff reductions across the energy sector, it has been claimed.
According to retail watchdog Consumer Focus, it expected much bigger reductions in gas and electricity prices from the firm.
The organisation's energy expert Robert Hammond said: "This again raises the question of whether wholesale price cuts are being fairly passed on to consumers.
"To answer customers' questions over whether they are getting a fair deal, Ofgem must commit to a firm date for its long-awaited review of the wholesale market."
He added that the reductions were very disappointing considering wholesale gas prices peaked in July of last year and have fallen 53 per cent since then.
Meanwhile, the cost of electricity peaked in September 2008 and has fallen by 52 per cent.
British Gas dropped its electricity prices by ten per cent this week the last major energy provider to do so.
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