Moamer Kadhafi's son is refusing to name a defense lawyer, a top Libyan diplomat said Wednesday amid growing questions over the conditions in which Seif al-Islam is being held.
The International Criminal Court (ICC) must decide in coming months whether to agree to Libya's request to try Islam in a domestic court.
The dictator's son is being held by a militia in the town of Zintan and international rights groups have raised concerns because Islam has not had access to a defense team.
Ibrahim Dabbashi, Libya's deputy UN ambassador, told the Security Council that Islam could have a lawyer if he wanted and that Libyan law dictates that he could not be tried without an attorney.
"This matter is mainly because of Seif al-Islam who till now refuses to appoint an attorney to defend himself," Dabbashi said.
"The matter is not in the hands of the Libyan authorities but the defendant himself. There are no obstacles to hiring an attorney to defend him," the envoy added.
The ICC has appointed a lawyer for Islam in The Hague but the attorney has not had contact with Kadhafi's son who was detained after the dictator was killed in October last year.
The lawyer, Xavier-Jean Keita, has called on the ICC to disqualify chief prosecutor Luis Moreno-Ocampo from the case, alleging possible bias.
Moreno-Ocampo, whose term ends in June, told the council that his office will express any "reservations" about Libya's capability to the international tribunal on June 4. The judges could then ask for more evidence from Libya or other parties.
"We are reviewing the conditions," Moreno-Ocampo told reporters when asked about the Islam case.
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He said Islam wants to be tried in Libya and has asked authorities to let his family find a lawyer he can trust, the chief prosecutor said.
The International Committee of the Red Cross and the Human Rights Watch (HRW) group have been able to visit Islam in recent months.
HRW has "serious concerns" about the conditions in which Islam might be tried in Libya, said the group's justice director Richard Dicker.
"We did see him, months ago. We do not know if he's been afforded access to a lawyer since," Dicker said.
"So we have real concerns about the situation conditions in Libya and whether that will lead to a fair and impartial trial.
"I think it would be a loss for the Libyan people, first and foremost, to have a kind of rerun of the proceedings meted out for Saddam Hussein in Iraq, where no accountability is fairly established."
Moreno-Ocampo also said he has asked NATO for more information about five incidents in which civilians were killed during air-strikes last year as part of the campaign which helped bring down Kadhafi.
A UN commission of inquiry found that about 60 civilians were killed in the NATO airstrikes.
Security Council members Russia, China, India and South Africa have said the Western nations went beyond the mandate given by the council in conducting the strikes. The United States, Britain and France all say the strikes were legal.
Moreno-Ocampo said he could not investigate NATO's mandate. "But we are still collecting information about these five incidents," the chief prosecutor said. NATO was among those asked to provide information.
Libya's government has strongly defended NATO's action.