RTÉ News has learned the Commission for Energy Regulation (CER) is considering a gas price increase of between 35% and 40%.
The announcement follows a 17.5% interim increase in electricity prices, which will take effect from August.
The ESB sought and secured the electricity price increase as a response to ongoing volatility in the international energy market.
The increase in electricity prices will take effect from August and will cover the period until next January. After that, prices are likely to rise again.
The regulator said the increase was regrettable but inevitable.
Now RTÉ News has learned that gas prices could increase by more than 35%, once again a reflection of the market instability.
The regulator is considering splitting the price increase, with the first rise taking effect from 1 September, and a second hike in the new year.
Meanwhile, consumers have been questioning ESB's price increase.
The National Consumer Agency has questioned the draft decision by the CER to approve an interim price increase, given that the ESB's announcement yesterday of a €300m contribution to help offset electricity prices will not come into effect until January 2009.
'We feel that the current situation is not beneficial for consumers, as peak electricity usage times are usually in the months leading up to Christmas,' Ann Fitzgerald, Chief Executive of the National Consumer Agency, said.
'We would therefore be looking for the ESB's contribution to come into effect from 1 August to coincide with the interim price increase.'
The Irish Small and Medium Enterprises Association (ISME) says its members are in 'shock and awe' at the price increase.
It claims CER does not have the technical expertise to evaluate the need for energy price hike and is asking the Minister for Communications, Energy and Natural Resources Eamon Ryan to review the situation.
IBEC has also expressed serious concern over the rapidly rising energy costs. Danny McCoy, IBEC Director of Policy, said: 'IBEC is disappointed by the CER's lack of inclusive consultation and the phasing of a proposed introduction of a 17.5% price increase in electricity in just three weeks time.'
In the past year the fuels which are used for generating electricity have soared. Oil has almost doubled in price and gas and coal are up even more.
