A Garda inquiry was under way last night after the charges were dropped by the DPP against Ms Jacqueline McIntyre, who was charged with arms possession.
The Opposition parties last night called on the Minister for Justice, Mr O'Donoghue, to make a full statement on the circumstances surrounding the dropping of the charges yesterday.
The Fine Gael spokesman on justice, Mr Jim Higgins, said the case was a serious matter where there was an attempt to smuggle firearms into the State at a very delicate stage in the peace process.
"There is an urgent need for the Minister to contact the Chief State Solicitor's office to establish the full facts of the case and for a public explanation as to why this happened," Mr Higgins said.
He said he would be tabling a special notice question for the Minister when the Dail resumes at the end of the month.
The Labour justice spokesman, Mr Brendan Howlin, said Ms McIntyre was charged with involvement in the attempt to import arms into the State by post from the United States.
"The accusations made by Ms McIntyre's solicitor that the case had been withdrawn on foot of accusations made against the gardai about the manner of Ms McIntyre's incarceration in Galway are obviously worrying, particularly as the DPP has decided not to proceed with the case.
"I am calling on the Minister to make a statement on the circumstances surrounding this decision and whether he intends to take any action on foot of it," Mr Howlin said.
A Department of Justice source said the matter was for the DPP and the Minister would not be commenting on it.