Britain's main energy suppliers from autumn will regularly inform customers about the best available tariffs to enable households to better meet their specific needs, the government said on Wednesday.

The commitments secured by the government will mean that the big six energy companies - EDF, E.ON, British Gas, Scottish and Southern Energy, Scottish Power and RWE nPower - will write to customers every year to specifically tell them what the best tariff is for them and how to get it, Deputy Prime Minister Nick Clegg said on Wednesday in London.

As of this autumn, your supplier will have to contact you with the best tariff for your needs. And if you call them, they'll have to offer you the best deal too, Clegg said, adding that energy companies had also confirmed a commitment to simplify tariffs.

The government said that vulnerable customers who are assisted by the Warm Home Discount scheme would be contacted twice a year.

Clegg also said the government was working with consumer groups to make it easier for people to club together and switch suppliers.

Consumers will be able to use their collective purchasing power to bring down bills, he said.

With over 120 different energy tariffs on offer, seven out of 10 customers are currently not on the best tariff for them, according to the government.

We can't control volatile world energy prices. But we can still help people get their bills down. So I can announce today that we have secured a landmark deal with the six big energy companies who cover 99 percent of customers, to give customers a guaranteed offer of the best tariff for them, Clegg said.

(Reporting by Henning Gloystein, editing by Jane Baird)