VALLETTA - Two men armed with a grenade and at least one gun hijacked a Libyan plane with 117 people on board Friday and diverted it to Malta before releasing everyone and surrendering, officials said.

The Afriqiyah Airways Airbus A320 was en route from Sabha in southern Libya to the capital Tripoli when it was taken over and forced to fly to Malta, sparking a four-hour runway standoff.

Maltese Prime Minister Joseph Muscat said the pair, probably of Libyan nationality, had given up a grenade and a pistol when they were arrested and a second pistol was found on the plane.

Libyan Foreign Minister Taher Siala from Libya's fledgling national unity government said the two were supporters of slain dictator Moamer Kadhafi, whose death in 2011 has plunged Libya into chaos.

Siala said they wanted to set up a pro-Kadhafi political party and would ask for political asylum in Malta, although Muscat said they had not done so.

The plane landed at Malta International Airport at 11:34 am (1034 GMT), with 109 passengers, six crew and the two hijackers on board.

All flights in and out of the island were initially shut down while the Maltese military conducted negotiations.

It stood immobile for around an hour on a secondary runway surrounded by military vehicles, before a door opened and a first group of women and children were seen descending from a mobile staircase.

Dozens more passengers followed minutes later.

Muscat said the hijackers were told there would be no negotiations unless all passengers were released.

After the release of all passengers and two of the crew members, the hijackers were holding only the four remaining staff "for a period of time," he said.

Following further negotiations "the hijackers agreed to free the remaining members of the crew and to surrender," he continued, adding that "the hijackers did not make any requests".

Armed Maltese military personnel were later seen storming the plane.

All passengers and crew members would be interrogated before a charter flight takes them back to Libya, Muscat said.

Hijackings have become relatively rare since the September 11, 2001 terror attacks on the United States led to increased security on flights.

Other recent hijackings have been carried out by individuals for reasons ranging from personal to political, and almost all ended swiftly and safely.

In the most recent incident in March, a man hijacked an Egyptair flight from Alexandria to Cairo and forced it to land in Cyprus so he could see his ex-wife.

Seif al-Din Mohamed Mostafa was described as "psychologically unstable" and claimed to have explosives strapped to his waist, but gave himself up after releasing fellow travellers.

In February 2014, an Ethiopian Airlines flight to Rome with 202 people on board was diverted by its unarmed copilot to Geneva where he asked for asylum.

During the crisis, Muscat spoke to Libya's prime minister-designate Fayez al-Sarraj, the head of the north African country's unity government.

Flights into Malta were diverted to different airports in Italy and outgoing ones were delayed.

Services later resumed after what Malta International Airport called "an unlawful interference".

Libya has been in a state of chaos since the 2011 overthrow of Moamer Kadhafi left warring militias battling for control of different parts of the country.

Forces loyal to a national unity government recently took control of the coastal city of Sirte, which had been a bastion for the Islamic State group since June 2015.

Western powers have pinned their hopes of containing jihadism in the energy-rich North African state on the government but it has failed to establish its authority over all of the country.

A rival authority rules the country's far east, backed by the forces under military strongman Marshal Khalifa Haftar who have been battling jihadists in second city Benghazi.

Only local airlines - banned from European airspace - operate in Libya, with flights to Tunis, Cairo, Amman, Istanbul and Khartoum.