Boris Johnson has joined other world leaders - including Russia's Vladimir Putin - at a summit in Berlin aimed at trying to resolve an escalating civil war in Libya.
The rival heads of the two sides fighting for control of the North African state are also attending the long-awaited gathering.
They are respectively backed by different foreign powers in a conflict that risks turning Libya into the latest proxy warzone after Syria.
Before the talks even began, rebel forces blocked oil exports from Libya's main ports, ramping up pressure on the internationally-recognised government of Prime Minister Fayez al Sarraj .
German Chancellor Angela Merkel, who is hosting the meeting, hopes to convince the warring factions, with the help of the United Nations, to agree on a lasting ceasefire.
This could include the deployment of the UN-backed peacekeeping force to oversee the implementation of any enduring truce.
But diplomats are not expecting a significant breakthrough this weekend.
The dialogue in Berlin is seen as the start of a process to try to resolve the past nine months of increasingly dangerous conflict.
A US official travelling with Secretary of State Mike Pompeo, said: "I think it's so complex and the heels are so far dug in that I would have moderate expectations as we go into this."
Libya has been consumed by conflict and instability since the ousting of Colonel Muamar Gaddafi in an uprising in 2011 that was supported by Britain, France and the US.
Since last April, fighting has spiked again between forces loyal to the Government of National Accord (GNA) in Tripoli and the so-called Libyan National Army (LNA) that supports would-be strongman Khalifa Haftar , a former Libyan general.
The UN-recognised government is being variously supported diplomatically, financially and militarily by Turkey, Qatar and Italy.
On the other side, Russia, the United Arab Emirates, Egypt and France are helping Mr Haftar.
The violence over the past few months has left thousands of people dead or injured and forced some 140,000 civilians to flee their homes, raising the possibility of a new wave of migration across the Mediterranean to Europe.
It is also creating a security vacuum into which extremist groups are able to flourish.
Turkish President Recep Tayyip Erdogan used this threat to warn European allies of what he viewed as the danger of not backing the Tripoli government.
He said the European Union's failure to adequately support Prime Minister al Sarraj would be "a betrayal of its own core values, including democracy and human rights".
"Europe will encounter a fresh set of problems and threats if Libya's legitimate government were to fall," President Erdogan wrote in an article for the Politico website.
"Terrorist organisations such as ISIS and al Qaeda, which suffered a military defeat in Syria and Iraq, will find a fertile ground to get back on their feet."
In a joint initiative, Turkey and Russia have brokered a ceasefire but Mr Haftar walked away from talks in Moscow this week aimed at finalising the truce agreement.
A furious President Erdogan has accused him of fleeing and said he would "teach (him) a lesson" if he resumed fighting.
World powers are trying to mediate a lasting ceasefire at the international conference in Berlin, which President Erdogan will attend. Other leaders present include President Emmanuel Macron of France.
UN spokesman Stephane Dujarric said at a press briefing on Friday: "We hope what comes out of Berlin is renewed demonstration of international unity in supporting the intra-Libyan political process, ending foreign interference, leading to full respect of the UN arms embargo."
The conference will aim to agree six points - including a permanent ceasefire, implementation of a much-violated UN arms embargo and a return to political efforts for peace.
Tribesmen allied to Mr Haftar imposed the oil export blockades from Friday at the eastern ports of Brega, Ras Lanuf, Hariga, Zuitina and Es Sider.
The move is reportedly in protest at a decision by Turkey to send troops to Libya to shore up Prime Minister al Sarraj.
While the focus of the day will be on Libya, the meeting will provide the first opportunity for Mr Johnson as prime minister to sit round a table with Russia's President Putin.
It is not yet known whether the two men will hold any bilateral talks.
Relations between London and Moscow are at a post-Cold War low in the wake of the attempted assassination of a former Russian spy and his daughter in Salisbury.
A failure by Mr Johnson to allow the release of a parliamentary report ahead of last month's election into alleged Russian meddling in in the UK caused an outcry.