British Gas is to increase the energy prices for those on standard tariffs by an average of 5.5% - or £60 a year.

The rise, which applies to both gas and electricity, will see the average annual dual-fuel bill go up to £1,161.

The company, the UK's largest energy supplier, said that 4.1 million of its customers would be affected.

The increase will take effect from 29 May and means British Gas is the first of the major suppliers to raise prices this spring.

It last increased its prices in September, when domestic electricity prices were raised by 12.5%. British Gas blamed government policy for part of that rise, a suggestion that was rejected by ministers.

'Pressure on bills'

British Gas said it had to lift prices following a rise in the cost of producing energy - including wholesale costs.

The company pointed to a similar decision by energy regulator Ofgem, which recently blamed wholesale costs for the rise in the default tariff for those with prepayment meters.

Mark Hodges, chief executive of Centrica Consumer, of which British Gas is a part, said: "We fully understand that any price increase adds extra pressure on customers' household bills. This increase we are announcing today is reflective of the costs we are seeing which are beyond our control."

He also blamed the extra charges it faced as part of government policy, such as the introduction of smart meters and emissions targets.

"Government policies, intended to transform the energy system, are important but they are putting pressure on customers' bills. We believe government should level the playing field so the customers of all suppliers pay a fair share of energy policy costs," Mr Hodges said.

"We continue to encourage government to consider moving these costs out of energy bills altogether and into general taxation."

Price comparison websites, which make money from customers switching suppliers, are predicting that other energy companies will follow the British Gas price rise.

Stephen Murray, from Moneysupermarket, said: "No doubt we will see speculation on which supplier might follow and how consumers need protection from rip-off prices."

Ed Molyneux, head of research for switching service Look After My Bills, said: "The data is clear, there is simply no justification for price hikes now, especially when British Gas put their prices up last year. Costs are still under the peak that triggered the first round price rises last year."

'Scrapping' standard variable tariffs

Energy firms have faced pressure from politicians over pricing, and the use of standard variable tariffs which have been deemed poor value for consumers.

British Gas has scrapped standard variable tariffs for new customers - following similar moves by E.On and Scottish Power.

Those British Gas customers already on fixed-term contracts who fail to opt for a replacement when the deal ends are now put on a separate default tariff.

This so-called Temporary Tariff will also rise by £60 on 29 May. At an average of £1,136 a year, it is slightly cheaper than the standard variable tariff used by existing customers.

Centrica's Mr Hodges said: "We also continue to call on Ofgem to end the standard variable tariff across the market which would encourage customers to proactively seek the best energy deal for them."

Although it is not specifically raising energy prices, E.On recently announced changes to how it bills customers which will see the average standard variable tariff rate rise by £22 a year from 19 April.