Tripoli, Libya (CNN) -- Libya's transitional government has hedged its claims that a mass grave had been found behind a notorious prison, telling reporters Monday that some bones found there were too large to be from humans.
"Some investigations have been conducted on this mass grave specifically, and there has been no conclusion yet," said Jamal Ben Noor, a senior official with the Justice and Human Rights Ministry. Ben Noor said the site reported behind Abu Salim prison in Tripoli "could be something else," because the bones found here are bigger than normal human remains.
Officials with the National Transitional Council, the movement that ousted longtime Libyan leader Moammar Gadhafi in August, said Sunday that it was investigating whether a mass grave had been found behind Abu Salim. Human rights groups say Gadhafi's government put down a 1996 uprising at the cost of hundreds of lives -- a toll the regime never acknowledged -- and the NTC said Sunday the grave may hold as many as 1,270 bodies.
But a CNN team that was brought to the muddy field with other news outlets found only what appeared to be animal bones. The NTC has called on international governments to help it investigate the site, which was discovered by revolutionary forces on August 20, said Kamal el Sherif, a member of the transitional government.
Ben Noor said officials "should wait and give it more time until we finish the investigation." He said the justice ministry is investigating a number of similar sites and may form a special committee of experts to review the finds.
Abu Salim's prisoners rioted over poor conditions and restricted family visits in June 1996, seizing a guard and escaping from their cells. Guards on the rooftops responded by opening fire on prisoners in open areas, former prisoner Hussein Shafei told Human Rights Watch in an interview years later.
Security officials ordered the shooting to stop and feigned negotiations, but officials instead called in firing squads to gun down the prisoners, Shafei said. After the inmates agreed to return to their cells, they were taken to prison outdoor areas, blindfolded, handcuffed, and shot, he recounted.
Gadhafi's government denied any crime had taken place. When some families filed a complaint against the government in 2007, Human Rights Watch said, the government offered them compensation in exchange for their silence. The families refused, calling it a bribe, and instead began holding protests each Saturday in Benghazi, one of the spots where the Libyan unrest began this year.
"There is a lot more to be done to reach the actual truth of this massacre," said Dr. Salem Fergani, one of the NTC officials who reviewed the site.
Family members of the Abu Salim victims were at the site on Sunday, and former guards at the prison are cooperating with an investigation, said Abdul Wahad Gady, a member of the military council in charge of the site. Gady said Sunday that efforts to excavate the site would only begin once "the proper team of experts, consultants and forensic teams" was in place.
At first, said Gady, inmates' bodies were buried inside the prison walls, but moved outside the walls in 1999.
CNN's Mohammed Tawfeeq and Phil Black and journalist Mohamed Fadel Fahmy contributed to this report.