Prime Minister Julia Gillard on Monday urged Libyan authorities to release an Australian lawyer accused of spying, as Canberra ramped up diplomatic efforts to secure the woman's freedom.
Melinda Taylor was detained on Thursday after meeting Seif al-Islam, the detained son of slain dictator Moamer Kadhafi, as part of a four-person team from the International Criminal Court (ICC).
"I am very concerned about the detention of Ms Taylor," Gillard told reporters.
"We are calling on the Libyan government to expedite the end of Ms Taylor's detention."
Gillard said while she had been assured that Taylor was safe and well, Canberra wanted to see her detention "come to an end as quickly as possible" and had dispatched to the country its ambassador-designate to Libya.
Australia would also work with Spain, Russia and Lebanon -- whose nationals comprise the other members of the ICC team -- to raise its concerns, she added.
Earlier Foreign Minister Bob Carr said he had spoken to Libya's Deputy Foreign Minister Mohammed Abdel Aziz to raise his concerns about Taylor, who has so far been unable to speak to consular officials or her husband.
"I said that her welfare is very, very important to us," Carr told the Australian Broadcasting Corporation.
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Australian officials would not comment on the allegations against Taylor, reported to be 36, who was detained after a meeting with Seif in the town of Zintan, some 180 kilometres (110 miles) from Tripoli.
Ahmed Jehani, Libya's envoy to the ICC, has said that Taylor is in detention because she was found "exchanging papers with the accused Seif al-Islam".
Jehani alleged that Taylor was carrying a pen camera and a letter from Mohammed Ismail, Seif's former right-hand man who is now on the run.
Jehani said the letter contained drawings and symbols, a "code" that would only be understood by the sender and the intended recipient, Seif.
"According to Libyan law, it would be spying, communication with the enemy," the envoy said.
Carr said he had been told that Taylor was not being held in jail or under arrest and that she was in good health.
She was "being detained not by the militia, not by the freedom fighters but by the judicial police as they are called and she is therefore the responsibility of the attorney-general of Libya", he said.
In a statement from the foreign ministry, Taylor's parents said their thoughts were "very much with our daughter, Melinda, and her colleagues" but added that they would not comment further publicly.
The ICC team was in Libya to help Seif choose a defence lawyer and the court has said that the visit was authorised by Libya's chief prosecutors. The Hague-based ICC wants to try Seif, 39, for crimes against humanity.
But the new regime in Libya wants to put Seif on trial in a local court, while ex-rebels in Zintan who are holding Kadhafi's son are refusing to send him to Tripoli for fear that he might escape.