A court has been told that the Public Prosecution Service deliberately failed to disclose to defence lawyers the existence of a so-called supergrass in a police anti-drugs investigation.

The claim, which was dismissed by a PPS lawyer, was made at North Antrim Magistrates’ Court when the case of 13 men and two women from Northern Ireland and England was mentioned before District Judge Richard Wilson.

It was alleged that one co-defendants, arrested in September 2010, Sean McManus from Portstewart, was seen last year entering a police station in Northumbria.

The lawyer described McManus as being “an assisting offender since April 2011” and said the information only became available after he was seen entering the police station in the Newcastle area of north east England. The lawyer said McManus’s role as an assisting offender was discovered “by sheer accident”.

A lawyer for one of the other defendants described McManus as being “essentially a supergrass”.

One defence lawyer said there had been “a mendacious approach from start to finish” by the PPS.

The use of “an assisting offender” has stirred-up anger among the defendents’ solicitors who accused the Public Prosecution Service of keeping their “supergrass” evidence a secret from both courts until it “leaked out accidentally.”

Demanding their clients be freed to protect their civil liberties or the case be brought to trial straight away, the defence teams settled for a shot across the bow from Coleraine District Judge Richard Wilson who gave the PPS just four weeks to prepare their case or face having all charges dismissed against the accused.

The Coleraine and Portstewart men and women are listed on court papers as Shaun McManus, Annu Vig, Louise Austin, Marion Hughes, Sheldon Lewis, James Platt, Daniel Morrow, Liam McManus, Ruairi McGlade, Matthew McGookin, Aidan Austin and a twelfth man whose identity has been protected by the court facing a host of charges including intent to supply.

The case against the 12 North Coast defendants was heard at Coleraine Magistrates Court on Monday where district judge Richard Wilson listened to no less than seven solicitors condemn the PPS for leading the courts on “a merry dance”. They claimed the deal with McManus was made back in April 2011 but the Crown was still unable to proceed with the case until September – nearly two years later.

A spokesman for the PPS denied any underhand dealings with the court and revealed that they could be ready for PE as early as May and that a crucial piece of evidence – a forensic accounting report from Price Waterhouse – would be ready on Tuesday, enabling the department to come to a decision.

The Derry based defendants – Kevin Gerard Whoriskey, 28 , 24-year-old Emmet Ryan Donaghey, and Brendan Joseph Harkin, 29, face a total of 14 charges including possessing ecstasy, and possessing the drug with intent to supply.

Speaking at Londonderry Magistrates’ Court Ciaran Shiels, of Madden and Finucane Solicitors, who represents Mr Whoriskey told the court that one of other 12 defendants had “been co-operating for some considerable time and has been co-operating under the Serious Organised Crime and Police Act 2005 with a view to becoming essentially a supergrass.”

He also said that various defence representatives were concerned that the full picture in this investigation is being kept from the district judges, and various forensic reports by police investigators in the case have yet to be completed, 18 months after the arrests.

The district judge Barney McElholm adjourned the case against the three Derry defendants until the March 8.