THE ESB's fuel purchasing strategies limited last week's price reductions for households, according to a report from the Commission for Energy Regulation (CER).

The 10% price cut was derided by some commentators, who pointed out that Irish electricity prices would still remain among the highest in Europe.

But the CER's price review paper indicates that its work was hampered by the fact that the ESB had fixed the price of 76% of its fuel requirements through hedging arrangements at the height of last year's energy price spike.

The review concluded that, because of this, the ESB would be forced to sell power at a loss if prices were cut by more than 0.5%, which would have implications for the profit margins of its competitors Bord Gáis and Airtricity.

In the end, the regulator slashed fixed network charges to achieve the 10% reduction, which had been promised by energy minister Eamon Ryan before the price review even began.

A CER spokesperson denied that the review had been influenced by external factors.

"We wouldn't agree with that. We have to take on board the concerns of customers and licensed operators when reviewing our tariffs," he said.

The ESB defended the company's hedging strategy, arguing that it provided price security to customers.

Meanwhile, Bord Gáis increased its domestic customer numbers by 66% last week. It now has 75,000 customers, 60,000 of whom have signed up over the past two weeks.