Ulster Television is preparing for a court battle with the British Ministry of Defence after British government lawyers obtained an injunction preventing the screening of a documentary on the activities of military intelligence in the North.
The Insight programme was set to reveal details of covert intelligence operations and of a soldier who infiltrated the IRA.
The station was informed four hours before the documentary was scheduled for broadcast at 10.20 p.m. on Tuesday that the British MOD had been granted an injunction in the Belfast High Court.
Excerpts of the programme were screened earlier on UTV Live news and detailed extracts appeared in the Belfast Telegraph on Tuesday.
Mr Justin O'Brien, editor of the programme, said yesterday a legal challenge to the injunction was already in motion. It was hoped the programme could be screened next week, he added.
"We have been totally gagged and we will be fighting that. The legal process has already begun," said Mr O'Brien.
The injunction prevents the station giving any information about the unit's methods, operational techniques or "tradecraft".
If the station chooses to repackage the programme it must give the British government 24 hours notice of transmission and the authorities must also be afforded an opportunity to review the tape in advance.