A Libyan official said Sunday an Australian lawyer detained after meeting Seif al-Islam was being investigated for the crime of spying, as an ICC team arrived in Tripoli to try to secure her release.
"The delegation just arrived now to negotiate with the Libyan authorities and the prosecutor general for the (ICC) team's release," said Ahmed Jehani, Libya's envoy to the international tribunal.
An International Criminal Court team of four people on Thursday visited Seif al-Islam, son of slain dictator Moamer Kadhafi, in the town of Zintan, 180 kilometres (110 miles) from the capital, where he is in detention.
The ICC said in a statement on Saturday that the four had been detained after the meeting.
But Jehani said that only two members of the team, Australian Melinda Taylor, and her Lebanese interpreter, Helen Assaf, were in detention, while two men, a Russian and a Spanish national, stayed behind out of their own accord.
"They arrested just two, the others stayed voluntarily," said Jehani.
"Melinda was arrested because she was surprised exchanging papers with the accused Seif al-Islam," he said, adding that her Lebanese interpreter was being held as an "accomplice."
"She (Melinda Taylor) had a pen camera and a letter from one of the men most wanted by the Libyan judiciary," Mohammed Ismail, the former right hand man to Seif who is now on the run, he added.
Jehani said he had seen the letter which consisted of "drawings" and "symbols," a "code" which cannot be understood except by the person who sent it and the intended recipient, Seif.
"She is under investigation because she committed a crime. According to Libyan law, it would be spying, communication with the enemy."
Taylor works with Xavier-Jean Keita, the defence attorney appointed by the ICC. Contacted by AFP, Keita declined to make any comment.
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The team was there to help Seif choose a defence lawyer and that the visit was authorised by Libya's chief prosecutors, according to the ICC.
But Taylor's wardens, members of the same Zintan brigade that captured Seif, say she should have declared the documents instead of sneaking them in.
Australian Foreign Minister Bob Carr called on Sunday for her release.
"Australia wants Libyan authorities to grant immediate consular access to Melinda Taylor and provide every assistance in securing her release."
ICC president Judge Sang-Hyun Song noted on Saturday that his staff have "immunity when on an official ICC mission."
"We are very concerned about the safety of our staff in the absence of any contact with them.... I call on the Libyan authorities to immediately take all necessary measures to ensure their safety and security and to liberate them."
Jehani said: "The Libyan authorities should respect the immunity but Melinda broke the law in a very grave manner."
Jehani told AFP that he was working in conjunction with the ICC delegation for the team's release and that he hoped the issue could be settled "amicably."
The Hague-based court wants to try both Seif, 39, and his late father's spymaster, Abdullah Senussi, for crimes against humanity committed while trying to put down last year's bloody revolt.
But the new regime in Libya wants to put Seif on trial in a local court.
The ex-rebels in Zintan who have been holding Seif since they captured him on November 19 have refused to transfer him to Tripoli because they fear he would escape from the capital, where they say security is weak.
Kadhafi was captured and killed by rebel forces on October 20 as his regime collapsed.