Image copyright Getty Images Image caption Customers can now phone or write, as well as go online, to reclaim money

Millions of energy customers who have money left in old accounts are again being encouraged to reclaim it.

The energy industry launched a website in September, in an effort to hand money back to three million customers who are owed it.

Now they are being given a telephone number and a Freepost address to use as well.

It is thought the customers are owed an average of £50 each, as a result of switching accounts.

Energy UK, which represents the industry, said millions of pounds were handed back to customers when the website was launched in September.

However, it said not everyone was online, so it was coming up with other ways for customers to claim.

Warning

"This campaign spreads awareness and makes it easier for consumers to check whether they are owed money or not," said Lawrence Slade, the incoming chief executive of Energy UK.

The campaign was welcomed by the regulator, Ofgem, although it warned the energy companies not to let the money build up again.

"Suppliers must now do everything within their powers to return the money and prevent a similar situation from happening again," said Philip Cullum, consumer partner at Ofgem.

"Ofgem will continue to monitor suppliers' progress and keep the need for action under review," he said.

Anyone who thinks they may be owed money can call the My Energy Credit helpline on 0370 737 7770.

Or they can write to:

Freepost RTHL-ZYBU-KBCC

My Energy Credit

47 Aylesbury Road

Thame

OX9 3PG