Updated

Libya's prosecutor general said Wednesday he has ordered ousted dictator Moamer Kadhafi's son Seif al-Islam to be transferred to Tripoli from Zintan for a pre-trial hearing in the capital.

Seif al-Islam and more than 30 others including ex-intelligence supremo Abdullah al-Senussi are due to appear before the court in Tripoli on Thursday, accused of crimes during the 2011 revolt which toppled Kadhafi.

"We have sent a transfer order to the penal authorities concerned to send those persons implicated in Case Number 630, including Seif al-Islam," Abdulqader Radwan told a news conference.

"So far there have been no obstacles to his transfer."

The main charges against the suspects include murders committed during the regime's battle against the revolt that erupted in the eastern city of Benghazi in February 2011.

Kadhafi was captured and killed by rebels in his hometown of Sirte in October that year.

His son Seif al-Islam was captured in November by a group of former rebels from the mountainous region of Zintan, west of the capital, and has since been held there.

The North African country's interim authorities have tried several times to negotiate the captive's transfer to Tripoli, but so far in vain.

However, the authorities insist that Seif al-Islam is in the custody of the state.

Deputy prosecutor general Siddiq al-Sur stressed on Wednesday that all the prisons concerned came under the authority of the justice ministry.

"If the director of any such establishment refuses to obey orders, he will be pursued by the judiciary," Sur told reporters.

However, Seif al-Islam is also due in the dock on Thursday in Zintan itself on security charges.

Asked about the coincidence about the court appearance dates on Wednesday, Sur said only that "the prosecutor general's office was not officially informed about the date of the trial" in Zintan.

Talks were reported to be under way late on Wednesday for Seif al-Islam to be transferred to Tripoli for several hours on Thursday.

"This will depend mainly on security conditions," said a source close to the case who asked not to be identified.

Amnesty International, meanwhile, urged the "immediate" handover of Seif al-Islam and Senussi to the International Criminal Court.

"The referral of these cases to the Indictment Chamber (in Tripoli) brings us one step closer to the start of national trial proceedings... in violation of Libya's legal obligation to surrender him to the ICC," it said.

"It is understandable that the authorities may want to proceed promptly and try these individuals in Libya. But such trials today will not serve justice," Amnesty said.

The London-based organisation said: "Libya's justice system is in desperate need of an overhaul. There are serious concerns about the authorities' ability to ensure fair trials compounded by the precarious security situation in the country."