The European Union condemned a fresh outbreak of violence Sunday, two days after the collapse of a truce with the militia controlling the airport, which left five civilians dead according to local media.
A coalition of militias led by Islamist fighters launched an assault on the airport on Sunday, with clashes later spreading along the road to the capital.
By Sunday evening, fighting had subsided around the airport, security official Al-Jilani al-Dahesh told AFP, but clashes continued in the western suburbs of the capital, witnesses said.
"The airport was attacked this morning with mortar rounds, rockets and tank fire," Al-Dahesh told AFP.
"It was the most intense bombardment so far."
Dahesh said the militia which controls the airport -- based in Zintan, southwest of the capital, and seen by Islamists as the armed wing of liberals within the government -- responded with heavy fire.
Islamist militias have been joined by other armed groups, including the powerful Misrata Brigades, which played a key role in the 2011 UN-backed revolt that toppled and killed strongman Moamer Kadhafi.
The fighting has halted all flights and caused extensive damage to planes and airport infrastructure, with aviation officials saying Tripoli airport could be closed for months.
Pictures posted on social media showed a Libyan Airlines plane on fire as plumes of smoke billowed over the airport.
The carrier said on its Facebook page that one aircraft, a Bombardier CRJ900, was destroyed.
Another aircraft, an Airbus A330, was also later reported to have been destroyed by fire.
Loud explosions were heard in the city centre, 25 kilometres (15.5 miles) away, as battles raged along the airport road with rockets striking nearby homes.
- 'No military solution' -
At least five civilians were killed in the Qasr Bin Ghashir neighbourhood, Mohamed Abderrahman, from the local town council, told private television channel Al-Nabaa.
The rival sides are among several heavily armed militias which have held sway in the oil-producing North African nation for the past three years.
Relentless violence across Libya this year -- including a war against Islamists in the east launched by a rogue general -- has sparked fears of all-out civil war.
The European Union mission in Libya issued a statement Sunday urging fighters to lay down their arms and spare civilians.
"The EU is concerned about the protracted conflict over Tripoli international airport and urges all parties to exercise restraint, to abide by international law and to respect civilians," it said.
"The EU calls on all parties to find a peaceful resolution through dialogue and compromise... there is no military solution to the crisis in Libya... the only option is a political solution and a peaceful democratic process."
On Thursday, Foreign Minister Mohamed Abdelaziz pleaded for UN help to build up Libya's army and police force and to protect vital sites, including the airport and oil installations.
The fighting mirrors a deadly power struggle between liberals and Islamists in the General National Congress, Libya's parliament and top political authority.
A new parliament was elected last month after the GNC was repeatedly accused of trying to monopolise power.
Results of the vote had been due to be announced Sunday, but the electoral commission announced a delay until Monday.
The growing lawlessness in Libya has alarmed neighbouring states that fear a spillover of violence.
On Saturday, militants attacked a checkpoint on Egypt's border with Libya, killing 22 soldiers, the Egyptian military said.
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