FBI director Robert Mueller traveled to Libya, his office said Thursday, as U.S. investigators continue their probe there into last year's deadly attack on a U.S. diplomatic mission.

"The director was in Libya to discuss cooperation on several issues," said an FBI official who spoke on condition of anonymity, without addressing whether Mueller, America's top cop, was investigating the September 11, 2012 attacks in Benghazi.

Slain leader Moammar Gadhafi's son Seif al-Islam, wanted by the ICC for crimes against humanity, appeared for the first time in a Libyan court on Thursday on charges of "undermining state security," a judicial official said.

He was charged after a controversial June visit to Libya by an International Criminal Court team to help prepare his defense against the charges of crimes against humanity in the conflict that overthrew his father.

Five Libyans tortured under Moammar Gadhafi have filed legal complaints against a French technology firm that provided his regime with surveillance equipment, a rights group said on Tuesday.

An appeals court has meanwhile given the green light to a judicial probe into accusations of complicity against Amesys, said Patrick Baudouin, a lawyer for the Paris-based International Federation for Human Rights (FIDH).

A Libyan court Monday adjourned to February 11 the trial of Moammar Gadhafi's last premier al-Baghdadi al-Mahmudi, accused of killing civilians and financial crimes.

Defense lawyers had asked for the delay to allow time to summon witnesses and the judge demanded that all witnesses testify in a single hearing.

A weekend attack on an Italian diplomat in Libya caused no casualties but dealt a body blow to the government's efforts to woo foreign investors to rebuild the war-ravaged North African country.

The assault on consul Guido De Sanctis, which Rome denounced as a "vile act of terrorism," came four months after militants torched the US mission in Benghazi and killed four Americans, including the ambassador.

Italian Foreign Minister Giulio Terzi on Sunday condemned as "a vile act of terrorism" a gun attack on Italy's consul to Benghazi in eastern Libya from which the diplomat escaped unscathed.

"This was an attempt to destabilize the institutions of the new Libya," Terzi also said in a statement after consul Guido De Sanctis's bullet-proof car came under fire on Saturday.

Italy's consul to Benghazi in eastern Libya escaped unscathed after an attack on his bullet-proof car in the city on Saturday, Italian news agency ANSA reported, quoting local security sources.

The car in which the consul, Guido De Sanctis, was travelling was shot at when it stopped at a crossroads, but no one was injured, the report said.

The prime ministers of Libya, Algeria and Tunisia decided on Saturday to reinforce border security and join forces tackling regional challenges including terrorism, arms trafficking and organized crime.

The decision was taken by Libyan Prime Minister Ali Zeidan, Algerian Prime Minister Abdelmalek Sellal and Tunisian Prime Minister Hamadi Jebali during a meeting in the southern Libyan oasis of Ghadames.

The premiers of Algeria, Libya and Tunisia are set to meet in the Libyan oasis of Ghadames on Saturday to discuss security along their common borders, a Libyan official said.

"A tripartite meeting between the prime ministers of Algeria, Libya and Tunisia will be held on Saturday in Ghadames to discuss border security," the protocol official told AFP on Thursday.

The Libyan ambassador to France was attacked in his office Thursday, police said, adding they had made three arrests.

Ambassador Mansour Sayf al-Nasr was "slightly injured in the forehead," a diplomatic source said.