The company, which blamed soaring energy wholesale costs for the rises, will next month increase gas prices by 11.8 per cent and electricity prices by 8 per cent in central and southern Scotland and north-west England and by 9 per cent in other areas. Npower and British Gas have also announced big electricity and gas price rises. The Commons trade and industry committee plans to investigate big increase in wholesale gas prices which it says have had a knock-on effect on other energy bills. PIN//FT