Npower announces the largest price hike of all the Big Six energy suppliers
Npower is raising energy bills by an average of £64 – making its standard tariff even more expensive than it was before.
The hike is the largest of all the Big Six and will affect one million customers.
The 5.3% increase will come into effect on 17 June, sending the average gas and electricity bill to £1,230 per year.
Mark Todd, co-founder of Energyhelpline, said: "The most expensive standard tariff just got more expensive."
British Gas and EDF announced last month that they were increasing bills for more than 5 million customers between them.
Scottish Power then quickly followed suit.
SSE is the only Big Six supplier yet to announce an increase - though SSE and Npower are planning to merge.
Our tip: Switch your deal now! You can easily beat all these price hikes by locking in a fixed deal today. Find one here.
German-owned Npower – like the other energy suppliers - blamed increases in wholesale energy costs and government policy changes such as the introduction of smart meters and emissions targets.
Simon Stacey, managing director, domestic markets at Npower, said: "Announcing this price change today isn't a decision we've taken lightly."
He said the costs energy suppliers are facing - "particularly wholesale and policy costs which are largely outside our control" - have been on the rise for some time "and we need to reflect these in our prices".
* EDF hiking prices for 1.3 million households
* British Gas to increase prices for millions of customers
* Scottish Power blames smart meters as it makes the biggest price hike of all Big Six
When will prices go up?
British Gas' hike comes into effect on May 29 and will see bills go up by an average of £60 to £1,161 a year.
Scottish Power is increasing prices by 5.5% - or £63 on average - for nearly one million people from 1 June.
EDF has a 2.7% - or £16 - electricity price rise coming into effect on 7 June for 1.2 million customers.
Npower's 5.3% increase - an average of £64 - will hit one million people from 17 June.
Npower and SSE merger
The two companies announced their plan to merge in November last year – a merge which would create the second largest supplier after British Gas.
But the Competition and Markets Authority has said that could result in higher prices for customers.
Are you paying too much for your energy bills?
We compare prices from the Big 6 and many other energy suppliers, getting you the very best price.