New videos show Libyan security officials threatening Muammar Gaddafi's son Saadi in an effort to force him to talk, two weeks after footage emerged showing guards beating him in the same Tripoli jail.

The videos, posted on social media, are an apparent attempt to embarrass the government controlling Tripoli, one of the two rival administrations in strifetorn Libya. Tripoli officials insist prisoners in their custody are well-treated.

Saadi has been held in Tripoli's Hadba prison since he was extradited last year from Niger, on charges over the killing of a football player when he was head of the Libyan soccer federation during the rule of his father, and other crimes.

After the first video emerged, the Tripoli government invited journalists to see Saadi in his cell last week to prove he was being well-treated. Saadi told Reuters he was fine but demanded he be released.

"I am not guilty. I am asking the officials to release me because I am not guilty," he said in the presence of government officials. "Everything is okay in the prison. They treat me well."

In one of the new, undated videos, an interrogator told Saadi: "You can talk by yourself or our guys will make you sit on a bullet from a 23mm gun so we will have all the information."

Another official tells Saadi: "Abdullah Senussi's ribs were broken when he entered here," referring to Gaddafi's former intelligence chief.

Saadi asks for his his blindfold to be removed, but an interrogator tells him: "Not now. Later."

The officials ask him about his connections to Islamist and other groups but Saadi says he is too afraid to talk. "They will hurt me. I swear to God they will hurt me," he said, referring to unidentified groups.

Tripoli officials could not be reached for comment. State prosecutors say they have launched an investigation in an atttempt to identify the guards responsible for the beating shown in the the first video.

Last month, a Tripoli court sentenced another son of Gaddafi's, Saif al-Islam, to death in absentia. Since Gaddafi's overthrow and killing in 2011, Saif al-Islam has been held by a former rebel group in Zintan, a western region beyond Tripoli's control.

Other former Gaddafi regime officials sentenced to die by firing squad included former intelligence chief Senussi and ex-prime minister Baghdadi al-Mahmoudi. They are awaiting confirmation of the sentences by the Supreme Court.

Rights groups say the prosecutions of former regime officials were riddled with legal flaws.