AN IRA terrorist who claims he was involved in more than a dozen

killings while operating as a police informer was arrested yesterday.

Declan Casey, 39, was seized in Strabane, County Tyrone, just minutes

after RUC Chief Constable Sir Hugh Annesley insisted he had not been

free to kill while working for Special Branch.

Sir Hugh emphasised that his force would allow no life to be taken in

order to protect its intelligence system.

Casey made his claims to the Daily Mirror but Sir Hugh, while

confirming that Casey was once an RUC informer, refused to believe him.

He said: ''It is the primary duty of the RUC to protect life and the

suggestion that a police force with such vast experience in informant

handling would betray its principles, as inferred in the Daily Mirror

articles, has no basis in fact and I totally reject any such

suggestion.''

The Daily Mirror said later that officers from the RUC and the

Metropolitan Police had taken away all documents relating to the series

on Casey from the newspaper's London office.

Casey fled Northern Ireland last September for a new life near

Nottingham but returned to Strabane at the weekend disillusioned with

the isolation and anxious to see his wife Joan and four children.

He accepted that his return made him a target for the IRA but the RUC

reached him first. Casey was arrested at his father-in-law's home on

Strabane's fiercely republican Ballycolman estate.

Last night, he was being interrogated at Castlereagh, Belfast, by

police, including a chief superintendent heading a full-scale inquiry

into the affair.

Sir Hugh and Ulster Secretary Sir Patrick Mayhew discussed the

allegations at Stormont Castle yesterday. Outraged Unionists have

demanded that Casey be charged.

Ex-UDR soldier Mr David Pollock, 30, shot dead in September 1990 while

driving through Strabane to visit his girlfriend, was one of two victims

whom Casey claimed he warned the RUC about in advance.

The widow of another ex-UDR man allegedly murdered with Casey's help

said that she did not believe the allegations.

Mrs Kathleen Finlay's husband, Ronnie, from Sion Mills, near Strabane,

was killed two years ago. She said that her local police commander had

been directed by Sir Hugh to tell her there was no truth in the claims.

* Loyalist terrorists were last night blamed for a parcel bomb which

exploded at Post Office headquarters in Belfast.

Five similar devices were found in mail at the building's sorting

office and defused by the Army.