A spokesman for ESOT would not say whether the ESOT trustees intended to accept or even respond directly to the offer of a meeting, only that the disputed figures "were a matter for all shareholders". He added that Ryanair seemed to confirm in its letter that the company's offer document contained discrepancies.

The employees' share group said in a statement released Thursday night that it had been asked by the Irish Takeover Panel to clarify the Ryanair claim that Aer Lingus employees would receive on average 60,000 each out of 220m that would be realised by the sale of Aer Lingus shares.

The ESOT statement questioned the accuracy of the Ryanair claim and said that the offer would be worth as little as 14,000 to ex-employee ESOT members, without explaining how it calculated those figures.

A second letter sent by Ryanair, dated 27 October, reiterated the offer for a faceto-face meeting with O'Leary.

It claimed that the ESOT figures, which included 35m of borrowing costs, excluded 6.7m in "unexplained deductions". It also said that Ryanair was seeking clarification about how proceeds from a potential sale of Aer Lingus shares would be allocated.

An exact number of ESOT members has never been publicly confirmed. In a statement released Thursday by Aer Lingus, rather than ESOT, the company said that ESOT had "approximately" 4,665 members. No figure was quoted in the statement released by ESOT itself.

The letter from O'Leary concludes: "We therefore ask you to provide us with details of the exact number of ESOT members (divided between current and ex-employees of Aer Lingus), and also confirmation as to how the proceeds of Ryanair's offer will be distributed amongst these members who are either current or former Aer Lingus employees. This clarification will allow any confusion over the proceeds of Ryanair's offer to be removed."

An ESOT spokesman said that the group had handed the letter to the Irish Takeover Panel.