British Gas looks set to increase its electricity tariffs by 12.5pc this autumn which will affect millions of customers.

The hike will be introduced in September and will impact 3.1 million people.

British Gas, one of the Big Six energy giants, confirmed the price rise, which will take effect on September 15.

It will mean an average dual fuel bill for a typical annual household tariff will rise by £76 to £1,120 - a 7.3pc increase, according to British Gas.

The announcement was made after a blunder which saw the energy group mistakenly publish an incomplete statement about increasing electricity tariffs on its website.

Centrica-owned British Gas said the price rise is its first since November 2013 and the group pledged to help protect more than 200,000 vulnerable customers from the increase.

The increase comes soon after Centrica posted half-year results revealing that earnings from its consumer business plunged by more than a quarter after it lost 377,000 UK customer accounts in the first half.

Underlying operating profits from its UK home energy supply arm tumbled 26pc to £381m as the group said it was also hit by warmer than normal temperatures and the pre-payment tariff cap.

Centrica's overall underlying operating profits were 4pc lower at £816m for the six months to June 30.

The group said it held off from the price rise a for 'up to six months longer than some of our competitors'.