The dispute between ESB and its deputy chairman, Mr Joe LaCumbre, continued yesterday with his legal team writing to the company asking them to reconsider a decision made on Tuesday concerning his position.

Meanwhile, the Department of Communications said last night Mr LaCumbre's position of deputy chairman was not based in legislation or company regulation.

A spokeswoman said: "The appointment is one made by Ministerial letter only". However she said specific issues relating to the position were for the ESB board.

On Tuesday, following strong words over the company's €511 million pension deficit, there was a dispute about who should chair board meetings in the absence of chairman Mr Tadhg O'Donoghue. Following a vote, Mr Eoin Fahy was selected for this role.

However, Mr LaCumbre, a worker director, claims he was effectively dismissed from his post and he is now considering his legal options. He said the intervention of Mr O'Donoghue led to his dismissal, a claim rejected by Mr O'Donoghue.

Mr LaCumbre has received the support of unions other than his own Technical, Electrical and Engineering Union (TEEU).

The national industrial secretary of the TEEU, Mr Davy Naughton, said members are angered "at Mr O'Donoghue's attempted office coup".

"We reject absolutely Mr O'Donoghue's contention that the board can decide on an ad hoc basis who chairs meetings. The procedural regulations are quite specific. They state that in the absence of the chair, his place is taken by the deputy chair and, in his absence, by the next most senior member of the board present," he added.

The Irish Times understands that Mr LaCumbre's legal representatives have written to the ESB board formally requesting that it rescind Tuesday's decision.