The number of complaints against the Big Six energy suppliers have fallen.

That’s according to new figures from Ofgem, which revealed British Gas, E.ON, EDF Energy, ScottishPower, SSE and npower received less than five million complaints last year.

That’s a 24% reduction – or 1.5 million fewer complaints – compared to 2014.

Despite the fall, Ofgem believes the number remains “too high” and is calling on all suppliers to continue to strive for further improvement.

While npower still received the most complaints out of the major suppliers last year, with 13,966 per 100,000 customer accounts, the figure “more than halved” compared to 2014, according to the regulator.

It continues to be at the bottom of the table “for practically all customer satisfaction measures” along with ScottishPower, with complaints at 12,900 per 100,000 customer accounts.

In December, npower was fined £26 million for customer service failings and given strict targets for improvement.

In the independent suppliers category, Utility Warehouse received the most complaints, with more than 7,600, followed by First Utility at 4,600.

Ecotricity received the fewest complaints at 1,612.

Trade body Energy UK said the fall in complaints reflect the investment companies have been making.

A spokesperson added: “Our members will continue to work hard until they can, hand on heart, say the industry consistently delivers the service customers deserve. Last year saw some particular challenges as companies upgraded systems and work is ongoing to resolve those issues.

“If a customer has a problem with their energy supplier they should speak to their company first. Increased competition means there are now over 30 suppliers so customers can find a deal that best suits them.”

Consumer body Which? however said many of the large suppliers “need to up their game as millions of customers are being let down with shoddy service and poor complaints handling”.

Executive Director Richard Lloyd added: “Our latest customer satisfaction survey shows that for the fifth year in a row, the smaller suppliers have wiped the floor with the Big Six so it’s clear companies need to take immediate action.”

Last month, figures released by the energy Ombudsman however revealed complaints about energy suppliers increased by 23% in 2015.