Esat Telecom has applied to join the Office of the Director of Telecom Regulation as a notice party to the judicial review taken by Eircom against the regulator. "Esat has applied to join the legal action in support of the regulator's direction that Eircom should face appropriate penalties for its failure to deliver leased lines according to contract timescales," Esat said in a statement.

An Eircom spokeswoman declined to comment on Esat's decision saying the case was sub judice. Earlier this month, Eircom was granted a judicial review of a directive issued by the telecoms regulator, which could cost the company more than £15 million (€19 million) in annual fines and question the viability of its leased line business. The dispute centres around a directive which removes a cap on penalties levied against Eircom for failing to meet service agreements to deliver leased line networks to competing operators.

Eircom has revealed it had a liability of £5 million in fines for failing to supply network connections to rival operators within a 26-day period in the past 12 months.