A senior executive at energy company Vayu has left the firm and is now pursuing legal action against its directors.

It is understood Rory O'Neill, who previously worked with Bord Gáis, left the company before Christmas after a disagreement with two of the Vayu directors.

Mr O'Neill is believed to be claiming a significant shareholding in the company. His case is on the commercial list of the High Court to be heard today.

The company claims it holds at least 5.25 per cent of the gas market but, according to industry observers, the firm will need extra capital to grow further. However, it does have some large customers, including CRH.

Vayu is licensed as a supplier and shipper of natural gas by the Commission of Energy Regulation. At present, it is the main Irish-owned rival to Bord Gáis.

The company hopes to have more than 10 per cent of the gas market by the end of this year. Managing director Tony Ennis said last year it was able to undercut Bord Gáis prices by between 5 and 10 per cent.

Vayu has promised to turn its attention to electricity in the long term. The company was formed to address the escalating energy costs in Ireland and provide industry a voice on energy issues.

Last year, it announced it had signed up nine gas customers out of a total eligible market of 230. The nine customers translate into € 4.2 million in annual turnover.

Vayu has links with the giant UK energy trading company Entergy Koch Trading, which trades over 27 billion therms of gas a year. This relationship allows Vayu to benefit from major purchasing power.

Several large industrial and commercial organisations have formed an independent co-op called the Irish Energy Co-Operative. Vayu is managing gas contracts on behalf of this group.