Speaking at a press conference in Tripoli on Thursday, the Libyan Prime Minister Abdurrahim el-Keeb said Melinda Taylor, an Australian ICC official, had compromised national security and should be investigated.
But he also said Libya is committed to cooperating with the ICC in the case of Seif Gaddafi who is awaiting trial for crimes against humanity.
He also criticized the ICC and said "the ICC should guarantee the professional morality and ethics of those sent to Libya."
"In return, the Libyan government expects the ICC to guarantee the professional ethics of its delegates who visit Libya, to respect Libyan laws and the sovereignty of the state," he said.
El Keeb spoke about what has become to be a well known fact that when she was caught red handed providing the accused of secret documents and electronic devices including tiny cameras and sensor equipments, Taylor was engaged in an act of spying that harmed the Libyan national interests.
He sai: "During the meeting with the defendant (Seif), Melinda Taylor handed over to the accused some documents and papers that compromise the national security of Libya.”
"These documents have nothing to do with the ICC mission. The ICC should guarantee the professional morality and ethics of those sent to Libya."
Taylor, one of four ICC officers who were on an official visit to Libya, had tried to deliver documents to Seif that were not part of her work for the court.
El-Keeb said the documents constitute "an offence punishable by the Libyan regulations."
He explained the incident again to reporters saying that on June 6, the visit by the Australian lawyer Melinda Taylor and three other ICC delegates had been arranged in cooperation with The Hague-based court and had the authorisation of the Libyan prosecutor general.
He added that the main purpose of the visit was to give the delegation an opportunity to meet Seif in his place of detention in the city of Zintan southwest of Tripoli, and to help him choose a defence lawyer.
"Miss Melinda Taylor handed the accused documents whose contents undermine the national security of Libya," el-Keeb said.
"The act... is considered an offence punishable by Libya's criminal law.
"The documents have nothing to do with the procedures of the International Criminal Court. And they are not linked in any way with the carrying out of legal consultations related to the case of the accused."
Libyan government spokesman Nassar el-Manaa said that they are being interrogated. "There is evidence that proves they have breached the law," he said.
The decision comes after the Australian foreign minister, Robert Carr, met el-Keeb, earlier this week, announcing a hope that Taylor would be released if the ICC issued an apology.
Manaa said such an apology would not prevent a criminal case being launched. "They (the ICC) should say: 'We have made a mistake,'" said Manaa. "When the interrogation is complete we will explain everything."
Taylor's three colleagues - a Lebanese translator, Russian diplomat and Spanish legal expert - have been told they are free to leave Zintan but have elected to stay with Taylor.
The British daily, The Guardian on Thursday termed Taylor's arrest as “spiralling into the most serious crisis in the ICC's 10-year history. Never before has one of its officials been arrested and held in detention."