A militia of Libyan ex-rebels seized control of Tripoli International airport on Monday, surrounding planes with tanks and grounding all flights after their leader’s apparent arrest, officials said."It is total confusion. Everyone is fleeing. Several armoured vehicles and tanks are positioned on the tarmac, blocking traffic,” an official at the airport told AFP."Cars mounted with anti-aircraft guns and armed men are surrounding the aircraft and preventing them from moving,” another official said, adding that some passengers were forced to leave planes.The official Lana news agency, citing witnesses, confirmed the "assault” by gunmen who fired into the air and slightly wounded an airport employee, causing panic among travellers.It said the motive of the gunmen was to pressure the government to explain the whereabouts of their leader, Abu Ajila al-Habshi.The attack forced the diversion to Tripoli’s Matiga military air base of some flights, including to and from Amman, Istanbul, Rome and Vienna, according to officials and flight monitoring websites.An AFP correspondent at the scene said the situation was calm but tense, with armed men still on the tarmac. Witnesses reported that trucks mounted with heavy weapons were parked under some airliners."Members of the Al-Awfya brigade entered the plane. They were fully armed and they forced us off,” Ahmed Loshta, a Tripoli resident who had been due to fly to Italy, told AFP."Some armed people occupied the runway. There was a truck with a machinegun mounted and individuals carrying AK-47s. They want somebody to be released,” added Saleh Kawas, a Syrian who had been due to leave for Jordan.Mohammed al-Harizi, spokesman for Libya’s interim government, said earlier that an investigation had been launched to determine the circumstances regarding the Al-Awfya brigade commander.Tripoli’s security commission, which answers to the interior ministry, said it had nothing to do with "the disappearance and abduction of Colonel Abu Ajila al-Habshi” and that it was still tracking those responsible.The ruling National Transitional Council (NTC) is still struggling to fully integrate many Libyans who fought forces loyal to dictator Moamer Kadhafi, who was ousted and killed in October last year.The former rebel fighters have remained in organised armed brigades, taking upon themselves to ensure law and order in the absence of fully functional police and armed forces.The NTC took control of Tripoli airport in April from a coalition of Zintan brigades that had been guarding the facility since the capital’s liberation in August 2011.The militias secured many strategic sites in Libya after they defeated Kadhafi loyalists backed by NATO-led air strikes during last year’s Arab Spring-inspired revolution.The NTC has called for their handover, but several other similar militias of former rebels are still guarding important buildings and facilities in the North African country.Monday’s incident at Tripoli airport comes as Libya prepares to hold elections for a 200-seat constituent assembly by June 19, as pledged by the NTC.Flashes of violence, such as a deadly raid on government headquarters last month, have raised concerns over the capacity of authorities to secure the first election after decades under Kadhafi.Ethnic unrest in the south, calls for greater autonomy in the east and corruption are just some of the challenges facing Libya’s interim leaders.Since the start of the Arab Spring, elections in the region have benefited Islamists, including in Egypt, Libya’s neighbour to the east, and Tunisia to the west.