British Gas is keeping its current gas and electricity prices on hold until August.
The company said it was able to hold tariffs in the face of higher wholesale prices by cutting its costs.
However, Scottish Power has said it is raising its dual fuel prices by an average of 7.8% from 31 March. It blamed smart meters and low carbon energy costs for the rise.
Energy regulator Ofgem urged customers to shop around for a better deal.
Scottish Power's move makes it the third of the UK's big six energy suppliers to announce price rises.
- Scottish Power's standard electricity prices will increase by an average of 10.8% and gas prices by 4.7%. About one third of its customers - 1.1 million people - will be affected by the change
- Npower is raising its standard tariff electricity prices by 15% from 16 March, and gas prices by 4.8%
- EDF Energy cut its gas prices by 5.2% in January, but its electricity prices are due to rise by 8.4% on 1 March
