Energy provider E.ON has become the latest firm to unveil inflation-busting price rises for gas and electricity customers.
The German-owned company, which used to be called Powergen, said gas prices were going up by 15% and electricity by 9.7% from Friday. The changes will affect nearly five million customers.
E.ON's announcement follows other large price hikes this year by four other energy firms - British Gas, Scottish Power, Npower and EDF.
E.ON, which has a total of 5.5 million customers, said 550,000 on fixed price deals would be unaffected by the rises.
It added that the hikes would be delayed until April 1 for 670,000 "vulnerable" customers.
The firm blamed the increases, which had been widely expected, on rising wholesale energy costs. They have gone up by 60% over the past year, it said.
E.ON managing director Graham Bartlett said: "We realise the impact this price increase will have on our customers and we're doing everything we can to minimise this.
"Our announcement has been made in response to sustained pressures from the wholesale market."
A customer's average annual dual fuel will go up from £913 to £1,031 as a result of the rises.
