The ESB is to apply to the High Court on Monday to prevent the £1.9 billion takeover of Esat Telecom by British Telecom.

Mr Justice McCracken was told yesterday by a solicitor for the ESB that it was of "vital importance" to her client that the Esat purchase "be restrained as soon as is practicable". The judge granted Mr Mel Christle SC, for the ESB and its subsidiary ESBIT Limited, liberty to bring a motion on Monday for an injunction restraining British Telecom from purchasing or proceeding with the purchase of shares in Esat.

The ESB claims the purchase is contrary to a joint venture agreement made between it, BT and other parties on June 2nd 1998 and will seriously affect the commercial viability of Ocean Communications Limited, of which ESBIT owns 50 per cent and in which it has invested millions of pounds.

Also on Monday, the ESB will seek a mandatory injunction requiring BT to withdraw any offer made by itself or its servants or agents for Esat and a declaration that, insofar as BT purchases any shares in Esat, those shares are held by BT on constructive trust for ESB and ESBIT.

Moving the application yesterday afternoon, Mr Christle said it arose from the offer by BT to purchase Esat.

In an affidavit, Ms Nora Coary, solicitor for the ESB, said the proceedings arose from a breach of the joint venture agreement entered into between the plaintiff, BT and others on June 2nd 1999.

She said that, on January 11th last, the ESB became aware that BT had offered to pay $2.46 billion for Esat. She said Esat is in direct competition with Ocean, jointly owned by ESBIT and BT.

BT's action in seeking to purchase Esat was in breach of covenants contained in the joint venture agreement, Ms Coary said. It was of vital importance to the ESB that BT's intended action "be restrained as soon as is practicable".

Granting liberty, Mr Justice McCracken said the action had implications for Esat and he made the company a notice party to the proceedings.