UTV has threatened legal action against RTE if it attempts to boost its signal into Northern Ireland. RTE is currently carrying out work on its Cairn Hill transmitter in Co Louth to enable it to be received throughout the North.

While UTV and BBC Northern Ireland are received by 70 per cent of homes in the Republic, via cable MMDS and natural overspill, RTE is received by only 30 per cent of homes in the North, due entirely to the signal over-spill.

A political decision was made during the 1980s for RTE to be available in Northern Ireland as part of the Anglo Irish Agreement. The issue has since been discussed on the fringes of Anglo Irish talks.

Within the past few weeks UTV sent a solicitors letter to RTE claiming RTE would be in breach of copyright, especially in beaming Coronation Street into the North, where UTV has the rights.

What is annoying RTE management is that UTV has been available for many years in the Republic, broadcasting some of the same programmes, including Coronation Street.

A spokeswoman for UTV said it realised it could not stop RTE broadcasting in Northern Ireland. Nonetheless, there are copyright issues to be resolved, she said.

Even if RTE boosts its signal the topography of Northern Ireland means it can only reach Belfast via the cable system, Cabletel.

A spokeswoman for Cabletel said the company would like to offer RTE to its subscribers but could not until the copyright controversy is settled.

UTV has never faced commercial competition in Northern Ireland. For 20 years it held the Northern Ireland cable franchise, which it did not develop. The franchise recently went to Cabletel, which will bring commercial competition for the first time. Cable TV is now available in Belfast and this week the company started selling subscriptions in Derry. It aims to operate a cable service supplying television, telephone and other services.

Ireland is increasingly viewed as one television market of about five million people. It is believed that UTV earns between £8 and £10 million in advertising from the Republic. It is also in the strange position of having more viewers outside its franchise area than inside it, due to its reach in the Republic. E is not available in Belfast and other major centres in Northern Ireland it will lose out while campaigns include UTV in order to target the whole island. A spokesman for RTE said yesterday he found it "bizarre that UTV is taking this action at this time". RTE has responded "vigorously" and has rejected the claim E it is infringing copyright.

Meanwhile, it is believed that BBC Northern Ireland is not pleased that the new commercial channel in the Republic, TV3, has acquired the rights to the BBC's popular soap, Eastenders. While BBC Worldwide, which handles commercial enterprises, will be glad to have the revenue, BBC Northern Ireland faces the possibility of losing audience share.