The Libyan capital's only working airport has come under rocket fire just days after reopening following a UN-backed ceasefire between rival armed groups vying for influence in the oil-rich country.
The attack on Tuesday night underscored the fragility of the latest peace push in the North African nation, which has been beset by turmoil since the fall of dictator Moamer Kadhafi in 2011.
Several rockets hit the perimeter of Mitiga International Airport on the eastern outskirts of Tripoli without causing any casualties.
Flights were diverted to Misrata, some 200 kilometres (120 miles) east of the capital, the civil aviation authority said.
Mitiga airport had only reopened on Friday after it was forced to close for a week because of deadly clashes between rival militias in and around Tripoli.
The fighting has killed at least 63 people and wounded 159 others -- mostly civilians -- since August 27, dousing hopes of elections being held this year.
UN envoy Ghassan Salame sought to downplay the latest breach of a UN-brokered ceasefire announced on September 4.
"Despite a minor setback last night, the ceasefire was generally respected in the past nine days," said Salame, who reported 14 truce violations observed by the UN.
The envoy said the UN knew who fired the rockets at the airport, without naming them.
"The next time (if they reoffend), I will name them," he told a news conference.
Salame said the Government of National Accord (GNA) had formed a commission to implement security measures in Tripoli, in line with the ceasefire deal that includes the withdrawal of heavy weapons and militias from the capital.
"Some of these measures have begun to be implemented and others will be implemented in the coming days," he said, without providing further details.
- Battle for influence -
A UN-brokered agreement signed in Morocco in December 2015 establishing the GNA brought hopes of an easing of the chaos that followed Libya's 2011 revolution.
But divisions remain between the GNA and rivals including military strongman Khalifa Haftar, who is based in the east and refuses to recognise the administration's authority.
Thousands of families have fled the violence to nearby towns or have had to seek shelter in other districts of Tripoli, authorities have said.
Several rockets had already struck near the airport last month, forcing authorities to divert all flights to Misrata on that occasion too.
Tripoli has been at the centre of a battle for influence between armed groups with shifting allegiances since Kadhafi was overthrown and killed.
The UN Panel of Experts on Libya said in a letter to the Security Council on September 5 that armed groups have "increased their influence over Libyan state institutions, promoting their own political and economic interests".
"The use of violence to take control of state infrastructure and institutions -- and threats and attacks against public servants -- are widespread across the country and are particularly noticeable in Tripoli", it said.
"The violent competition to capture the Libyan state is hampering the political transition in the country," the panel said.
Mitiga airport, a former military air base, has been a civilian airport since Tripoli's main international airport was badly damaged in fighting between rival militias in 2014.
Since then only Libyan airlines have operated in the country, running internal flights and regular connections to a handful of nations, including Tunisia and Turkey.
Libyan airlines are banned from European Union airspace for "security reasons".
- Infrastructure hit by fighting -
The electricity network has been damaged by the recent fighting, exacerbating power cuts around Tripoli, that have lasted up to 24 hours.
Militias in the east have prevented rationing in their zones, worsening the shortages in the capital and southern Libya, the national electricity company said this week.
Internet and phone networks have also been interrupted, while the water supply has been cut for a week.
On Wednesday, France's ambassador to the UN Francois Delattre said his country believes it "essential" that presidential and legislative elections take place in Libya on December 10, in line with a timetable agreed in May.
Jihadist groups and people traffickers have taken advantage of the chaos to gain a foothold in Libya.
The Islamic State group claimed responsibility on Tuesday for a suicide attack a day earlier against the headquarters of Libya's National Oil Corporation which killed two employees.