PARIS — Despite pressure from international courts, NATO and rights groups, the Libyan authorities who are detaining a lawyer from the International Criminal Court and three members of the court’s staff say they will not be released until the lawyer answers questions about her dealings with Seif al-Islam el-Qaddafi, a son of the former dictator, a Libyan official in Tripoli said.

The lawyer, Melinda Taylor, and her three associates have been held under house arrest since last Thursday in the town of Zintan, where Col. Muammar el-Qaddafi’s son is held captive by militia fighters operating largely independently of the Libyan central government. The militia captured the son in the desert last November and has been holding him since then, awaiting an agreement on where he will be tried on a host of charges.

The four, who were sent by the International Criminal Court to visit Mr. Qaddafi by arrangement with his captors, are accused by the militia of bringing along suspicious documents and a camera disguised as a pen.

“Ms. Taylor had brought letters for Seif from two different people, dangerous people who are supporters of the old regime, and she had a page with drawings that looked like codes,” said Ahmed al-Gehani, a Libyan lawyer who accompanied the group to Zintan as the government’s liaison official for the court.