More are expected to follow suit and the moves come after similar rises last year.

Britain's dominant energy companies have been under scrutiny by the government, which is putting a price cap on standard variable tariffs to combat what it has called "rip off" energy prices.

Below are tariff changes so far this year (in alphabetical order):

NPOWER:

Npower, owned by Germany's Innogy, will raise its variable dual fuel bill by 5.3 percent as of June 17, impacting about 1 million customers.

The rise represents a 64 pound increase on annual bills and a direct debit customer on the tariff will typically pay 1230 pounds ($1,664) a year. The hike is made up of average rises of 4.4 percent on gas and 6.2 percent on electricity.

BRITISH GAS

Centrica British Gas is increasing its standard variable tariff for electricity and gas by an average of 5.5 percent from May 29.

The move will add 60 pounds ($85) to annual bills for 4.1 million customers on the tariff, raising them to an average of 1,161 pounds, the company said.

EDF ENERGY

EDF Energy, a unit of French utility EDF, said it will increase the cost of its standard dual fuel energy bills by 1.4 percent (or 16 pounds) to 1,158 pounds a year from June 7.

SCOTTISH POWER

Iberdrola Scottish Power said it will raise standard variable domestic gas and electricity prices from June 1 by an average 5.5 percent, or 63 pounds on a typical annual dual fuel bill.

The move will affect around a third of homes supplied by Scottish Power (around 960,000).

($1 = 0.7392 pounds)

(Reporting by Nina Chestney and Sabina Zawadzki; editing by Jason Neely and Alexander Smith)