* Energy suppliers to offer 4 tariffs each for gas, power
* Companies forced to put customers on best deal
* Ofgem wants consumer engagement to boost competition
LONDON, June 21 (Reuters) - A number of British consumers may be able to cut their energy tariffs from December under rules proposed by regulator Ofgem that it hopes will encourage competition.
The main energy suppliers all raised heating and power charges during the past exceptionally long winter, at the same time that austerity measures were already squeezing consumers' disposable income.
Prime Minister David Cameron made a personal pledge in October to force energy companies to offer customers their lowest tariffs, a promise the regulator is now trying to deliver.
"Our reforms today are the blueprint for the simpler, clearer and fairer energy market that consumers deserve," Andrew Wright, a senior partner for markets at Ofgem, said in a statement released on Friday.
"This will provide them with the choices they want alongside the simplicity they need."
Britain's energy companies will be forced to offer only four tariff options each for electricity and for gas and help customers find the cheapest offer available to them.
The rules are now open to public feedback and will come into force in December unless they are challenged, Ofgem said.
Six big energy suppliers control the bulk of the retail market and are often accused by the public of abusing their dominant position.
They include EDF Energy, Centrica, SSE , RWE npower, E.ON and Scottish Power.
Energy UK, the association representing the energy sector, said its members had already started offering clearer tariffs and fewer tariff options.
Ofgem is also asking companies to make customers' bills more engaging, a proposal the regulator said should mean consumers will take more interest in their energy usage and encourage them to switch suppliers more often.
"Part of the whole raison d'etre of the reform is to get people engaged with the market," a spokeswoman for Ofgem said.
"We will expect customers to switch to different deals and potentially different suppliers as a result of the reforms."
Consumer Futures, an association representing UK consumers, welcomed the proposals but said further changes were needed to make it easier for users to switch energy supplier.
"Consumers are not just going to wake up one sunny morning and decide that they trust and want to engage with the market," said Adam Scorer, Consumer Futures' director of policy and external affairs.
Ofgem is passing parallel rules to break up the stranglehold the six firms have on the market by forcing them to offer smaller firms access to their energy production and to reveal prices at which they purchase long-term supply.