Private windfarm developers who protested at the Government's awarding of green energy contracts to an ESB subsidiary this summer have lodged a formal complaint with the Competition Authority.

The Irish wind farmers' co-operative, Meitheal na Gaoithe, has accused the State-owned company of using its subsidiary, Hibernian Wind Power, to keep private developers out of the renewable energy market.

By subsidising Hibernian, the ESB succeeded in undercutting other bidders in the Government-sponsored Alternative Energy Requirement (AER) competition and excluding small-scale developers, the complaint argues.

The ESB has rejected the allegations of anti-competitiveness against it or Hibernian as "totally unfair".

"We will vigorously contest the allegation," a spokesman said yesterday.

Earlier this week, the Minister for Communications, Marine and Natural Resources, Mr Ahern, acknowledged allegations of cross-subsidisation within the ESB but said that they were "untrue".

"We had that independently checked and verified and that's not true," he said.

The wind farmers' complaint also argues that the awarding of additional electricity generation capacity to the ESB conflicts with the State-company's target of reducing its share of the overall generating market to 60 per cent.

"The OECD and others have said the ESB should have no additional generating capacity if they are ever to get near this target," said Mr Tommy Cooke, chairman of the wind farmers' co-operative.

Yesterday, the ESB said it was committed to reaching this target and that "this will include any share of the wind sector".

An ESB spokesman said Hibernian has a "very small share of the wind sector".

After the conclusion of the AER 6 competition, he said that Hibernian's share of all AER competitions would be under 20 per cent.

"No-one could validly make any claim that this is an unfair share for the leading energy company in Ireland," he added.

But Mr Cooke said: "The ESB has won contracts for over 50 per cent of the megawatts awarded in the AER 6 large-scale wind competition to date.

"They won all the offshore capacity as part of the Kish consortium and were even awarded a contract in the small-scale sector."

The ESB spokesman said that the rules of the competition "specifically allowed for this".

Mr Ahern this week reiterated that "the system is totally transparent, totally independent of the Minister and totally based on lowest price".