Libya's UN-backed Prime Minister-designate, Fayez al-Sarraj (R), is greeted by unidentified officials upon his arrival in Tripoli on March 30, 2016
Tripoli (AFP) - The head of Libya's UN-backed unity government arrived in Tripoli on Wednesday following months of mounting international pressure for the country's warring sides to allow him to start work.
UN special envoy Martin Kobler hailed the arrival of prime minister-designate Fayez al-Sarraj, urging a "peaceful and orderly handover of power" and praising his "exceptional personal courage".
Sarraj, a businessman named the government chief under a UN-brokered power-sharing deal in December, arrived by sea with a naval escort along with several members of his cabinet.
Speaking in Tripoli, Sarraj said he would make "reconciliation and the settlement of security and economic crises" his top priority.
Libya has had two rival administrations since mid-2014 when a militia alliance overran the capital, setting up its own authority and forcing the internationally recognised parliament to flee to the country's remote east.
International leaders, increasingly alarmed by the rise of jihadists and people-smugglers in the impoverished North African state, have urged Libya's political rivals to support the unity government.
But so far the two administrations have refused to cede power.
A presidential council formed under the December deal confirmed on its Facebook page that Sarraj and several other members had "arrived safe and sound in Tripoli".
Kobler tweeted that their arrival "marks important step in #Libya democratic transition & path to peace, security and prosperity."
Dressed in navy blue uniforms with white sailors' caps, several senior marine officers held a guard of honour to welcome Sarraj at the naval base where they docked.
Outside, armed vehicles and anti-aircraft guns bearing interior ministry insignia kept guard alongside gunmen in civilian clothes charged with providing security for Sarraj and his ministers.
- 'Another step forward' -
The EU's foreign affairs chief Federica Mogherini said Sarraj's arrival in the capital was "a unique opportunity for Libyans of all factions to reunite".
Italy, which has offered to lead a peacekeeping force in Libya if asked to by the new government, also welcomed the development.
"It is another step forward for the stabilisation of Libya," Foreign Minister Paolo Gentiloni said. "Further progress is now possible for the Libyan people based on the determination of the premier Sarraj and the presidential council."
Sarraj and his cabinet had previously been blocked from entering the capital by the authorities there, who even closed the airspace several times to prevent them flying in.
It was unclear if their arrival had been agreed in advance with the Tripoli government, which had announced on Friday a "maximum state of emergency" as Sarraj's cabinet prepared to head to the capital.
Tripoli residents reacted on social media to his arrival with a mixture of hope and sarcasm.
Twitter user @alladdinno said Sarraj's appearance in the capital "felt like when the things you ordered online finally arrive".
Facebook user Najiya said she hoped the new administration "could serve the country and its people".
- IS high priority -
The unity government announced this month that it would start working on the back of a petition signed by a narrow majority of Libya's elected lawmakers.
The United States and its European allies have threatened sanctions against those who undermine the political process.
And UN chief Ban Ki-moon called on Tuesday for anyone obstructing the peace process to be "held accountable".
Libya has descended into chaos since the 2011 ouster of longtime dictator Moamer Kadhafi, raising fears that the Islamic State group is establishing a new stronghold just across the Mediterranean.
IS has seized control of Kadhafi's coastal hometown of Sirte and launched a wave of attacks, both against rival Libyan forces and across the border in Tunisia.
The group claimed responsibility for two attacks last year in Tunisia -- on the Bardo national museum and at a beach resort near Sousse -- that killed a total of 59 tourists.
Western countries are considering military action against the jihadists in Libya but want a unity government to request help first.
The US Special envoy for Libya Jonathan Winer tweeted that the country's politicians "must now begin crucial work to address full range of #Libya's challenges".
Libya has long been a stepping stone for migrants seeking to cross the Mediterranean to Europe, which lies just 300 kilometres (185 miles) away, and in recent years traffickers have exploited the country's instability.
Libyan coastguards rescued 152 Europe-bound migrants from two vessels in trouble early on Wednesday, according to a spokesman for the Tripoli navy.
Around 330,000 migrants have landed in Italy from Libya since the start of 2014.