Centre of tripoli
121 killed, nearly 600 wounded in Libya fighting: WHO
Fighting in Tripoli has killed 121 people and wounded 561 since commander Khalifa Haftar launched an offensive earlier this month to take the Libyan capital.
Rival groups have been fighting in Tripoli for several days but clashes had been focused on the south of the city. Matiga airport lies in an eastern suburb.
Facebook is the main platform for news in Libya with officials, ministries and armed groups that effectively control the country posting statements there.
The attack was the second against al-Qaeda in the Islamic Maghreb in recent months.
The officials, speaking on the condition of anonymity, said that US Special Operation Forces captured the militant in Libya in the past few days.
On Wednesday, Johnson made his second trip to Tripoli to meet Seraj.
An airport spokesperson said commercial flights to the airport had been halted because of the violence.
The sources say al-Qaeda is now seeking to expand in Lebanon, particularly the northern city of Tripoli.
Libyans are on Saturday voting in their first and free national election in 60 years.
Nine months after the end of Libya's uprising, the country is going to the polls.
Representatives of the International Criminal Court arrived in Tripoli on Sunday.
Libyan militia surrounded Tripoli's international airport on Monday.