Lawyers working for an Aer Rianta director have written to the Taoiseach, Mr Ahern, expressing concern at what they contend is an error in the legislation that will allow the break-up of the State airports operator.

The alleged mistake is contained in section 12(12) of the State Airports Bill, 2004. This states that the person "carrying out the duties of the chief executive of Aer Rianta" should have their pay and conditions determined by section 29(4) of the Air Navigation and Transport (Amendment) Act, 1998.

But the State Airports Bill also amends section 29 of the 1998 Act. As part of that change, section 29 (3), not section 29 (4), is the one that determines the chief executive's pay and conditions.

Legal advisers to Aer Rianta worker director Mr Peter Dunne are understood to have written to Mr Ahern pointing out the error and expressing concern at it. Mr Dunne did not want to comment on this yesterday.He is opposed to the break-up as he believes it poses serious risks to the company and its assets. He has said that as a director he believes he would be obliged to go to court to halt the restructuring.

The Irish Times reported earlier this week that the mistake, in the State Airports Bill, could result in the legislation being amended to correct the error, which would require returning to both houses of the Oireachtas. It passed the Seanad stage on Wednesday.

The Minister for Transport, Mr Brennan, told the Seanad that Aer Rianta had written to him querying whether it might be a drafting error. However, he said the Attorney General's office had assured him that there were no errors in the legislation.

The Bill is now set to go to the President, Mrs McAleese, to be signed into law. Under protocol, the Taoiseach's office sends the bill to the President and it remains to be seen how it reacts to the letter from Mr Dunne's advisers.