A 25-year-old law student charged with transporting explosives to Northern Ireland remains in prison after a delay in approving a bail surety, while a political leader has called the decision to grant her bail deeply concerning.

Isobella Perrie Sullivan, of Abbeylands Park, Clane, Co Kildare, was charged with possession of explosives after gardaí intercepted a car she was driving near Carrickmacross, Co Monaghan, last Wednesday. The device, which contained Semtex and a timer power unit, was described as sophisticated and ready for use.

At a special court sitting in Trim on Friday, Sullivan was granted bail on conditions including an independent surety of €15,000, surrender of her passport, a night-time curfew, daily signing at a garda station, and a ban on contact with members of Saoradh and the New IRA. Her solicitor told the court she had been manipulated into carrying a bag north and did not know its contents.

When the case returned to Monaghan District Court on Monday, Judge Raymond Finnegan said no formal application to approve the surety had been received. Gardaí confirmed they were still carrying out inquiries. Sullivan, appearing by video link from the Dochas Centre in Dublin, expressed surprise that she was not being released. She was remanded in custody until 7 August.

Ulster Unionist Party leader Jon Burrows said the granting of bail was difficult to understand given the seriousness of the allegations. He noted gardaí had opposed bail and described the idea that her parents could supervise her as absurd. Burrows intends to write to the Irish Justice Minister seeking assurances on how terrorist-related cases are handled and questioning whether the Semtex is recently manufactured or from old IRA stocks.

Northern Ireland Justice Minister Naomi Long praised the cross-border security operation that she said prevented serious injury or loss of life. She linked the foiled attack to recent incidents at police stations in Lurgan and Dunmurry and stressed that the threat from terrorism persists. She also highlighted the need to protect young people from radicalisation.