Libyan leader Moamar Gaddafi has been accused of bringing in soldiers from Chad to crack down on protests in which nearly 50 people may have been killed in the city of Benghazi.

Speaking exclusively to the ABC's The World Today program, a Libyan protester said he had witnessed children and young protesters jumping off Benghazi's historic Giuliana bridge to escape security forces.

"Twelve people died," the man, known as Mohamed, told The World Today, saying eight of the deaths happened when security forces attacked protesters in the middle of Benghazi.

In a separate incident at the Giuliana bridge, Mohamed said "there were security forces ... with military men from Chad, acting with force."

"He [Gaddafi] brought people, military men from Chad. People were jumping off Giuliana bridge in fear ... and the water was really deep ... children, I swear," he added.

The protests in Libya are the latest in a wave of dissent sweeping the Arab world in the wake of the revolutions in Tunisia and Egypt.

Mohamed said the protests were not organised but were sparked by youths turning out for Thursday's "Day of Rage" against the Gaddafi regime.

"We don't have here unions and syndicates or political parties, just youth going out on the "Day of Rage" (February 17) - maybe 48 died in Benghazi," he said.

Mohamed said "thugs" were being given cash and new cars to take to the streets and attack anti-government protesters.

"They get paid 5,000 and the latest model car just to get rid of these demonstrators," he said.

"There is no radio or TV that covers this news, and I think that there are people being captured from their houses at 3:00 and 4:00am. So there is no safety."

Earlier, six people were reported dead in Benghazi as Mr Gaddafi's regime sought to overshadow the opposition "Day of Rage" with its own rally in the capital Tripoli.

Geneva-based Human Rights Solidarity, citing witnesses, said rooftop snipers in Al-Baida - a city of 210,000 inhabitants - had killed 13 protesters and injured dozens of others on Wednesday.

But the Quryna newspaper, close to Mr Gaddafi's son Seif al-Islam, cited official sources and put the death toll at two.

Media bans and intermittent phone and internet connections have made it very difficult to verify events unfolding in Libya.

But a senior Libyan opposition figure exiled to the United States, who is in touch with protester, says accounts like those of Mohamed are accurate

Ibrahim Sahad is the secretary-general of the National Front for the Salvation of Libya and was a high-ranking military and diplomatic officer in the Gaddafi regime until he resigned in 1981.

He has been encouraging the protests through social media and says he knows Mr Gaddafi enlisted military forces from Chad to help in the crackdown a week before the protests began.

Mr Sahad says he has heard reports from Al-Baida that people were being imported from Chad a week ago, and that some of the forces which tried to quell the Benghazi uprising were not Arabic speakers.

He says the government has used live ammunition against protesters, and that Mr Gaddafi has sent people to destroy things to make it look like the protesters did it.

Shot from helicopters

"I was on the phone with a protester in Al-Baida and my information is first-hand information and I also contacted some [other] protesters in Benghazi," he said.

"The regime already used snipers, used helicopters in Al-Baida and they shoot from the helicopter towards the protesters.

"The hospital in Al-Baida is not receiving any more casualties. It is full with casualties. Today in Al-Baida seven people was killed. I don't have the number for those injured, [but] three people were injured in a very critical condition.

"Last night in Al-Baida five people were killed and today the funeral of those five people has been done with almost everybody in Al-Baida following the funeral.

"This is factual information which I am getting from there.

"In Benghazi last night Gaddafi sent some gangs to go to the main street in Benghazi to break cars, break the properties of people, even threatening the people in their homes, just trying to say that this is done by the protesters."

Mr Sahad says he resigned in 1981 when he witnessed Mr Gaddafi sending gangs to Europe to kill Libyans abroad.

"He killed Libyans in London, in Rome, Milan, in Athens. He tried to kill others in other cities. I know that Gaddafi during 40 years in his governing Libya he committed so many crimes against the Libyan people," he said.

"One of the crimes is killing 1,200 prisoners in three hours. He ordered to kill 1,200 political prisoners. This is Gaddafi's history. He is a criminal by nature and the international community is not saying much.

"I would like to say that what I see is way less than what I expected. I expected to hear the European government, United States of America as they are talking about human rights and talking about democracy ... to see them come forward to support the Libyan people.

"Unfortunately that is not taking place."

Mr Sahad says the US and the rest of the world has to respond to the situation in Libya in two ways.

"Number one is to put pressure on Gaddafi to stop using force against this demonstrations. The second is to send his ambassador back," he said.

"What we are seeing now in Libya is a regime that has no intention to have any mercy towards those Libyans who are protesting.

"I think to stop dealing with this regime is something we have precedent for. We knew that it happened before and I think it is the easiest or the simplest thing to do."

He says if Libyans stop protesting without ousting Mr Gaddafi, he will punish them.

"Inside Libya they know very well that they started this protesting because they were patient for more than 40 years now - 41 years to be precise," he said.

"They know that if they stop this demonstration before Gaddafi is ousted then that [he] will come and will start punishing them in a very brutal way."