A lawyer for the International Criminal Court (ICC) has been detained in Libya after she was found to be carrying suspicious letters for Muammar Gaddafi's captured son Saif al-Islam, a Libyan lawyer said on Saturday.

The Australian lawyer, named as Melinda Taylor, was part of a four-member ICC delegation that had travelled to the small western mountain town of Zintan where Saif al-Islam has been detained since his capture in the desert in November.

"During a visit (to Saif al-Islam), the lawyer tried to deliver documents to him, letters that represent a danger to the security of Libya," said Ahmed al-Jehani, the Libyan lawyer in charge of the Saif al-Islam case on behalf of Libya, and who liaises between the government and the Hague-based ICC.

"She is not in jail. She is being detained in a guesthouse, her colleagues are with her," he told Reuters.

He did not say what was in the documents but said they were from several people including Saif al-Islam's former right-hand man, Mohammed Ismail.

Jehani said the ICC team, which arrived in Libya this week and had received permission from Libya's prosecutor-general to visit Saif al-Islam in the secret location where he has been kept, had been searched before the meeting.

Without giving details, he said a pen with a camera as well as a watch with a recorder were found during the search. Asked whether she would be released soon, Jehani said: "I hope today."

An ICC spokesman was not immediately reachable for comment.

Western-educated Saif al-Islam, Gaddafi's one-time heir apparent, was captured by fighters from Zintan in Libya's southern desert in November, dressed as a Bedouin tribesman, and taken to their home town.

The ICC issued a warrant for him last year after prosecutors accused him of involvement in the killing of protesters during the revolt that toppled his father, who ruled Libya with an iron fist for 42 years.

Libya has resisted handing him over, saying he should be tried at home. In May, it filed a legal challenge, contesting the Hague-based court's right to try the case.

The ICC ruled this month that he could stay in detention in the North African country while the court decides if it has the jurisdiction to try him.-Reuters