Geneva (AFP) - Rival Cypriot leaders on Monday resumed UN-backed peace talks seen as a historic opportunity to end decades of conflict on the divided island, but the outcome is far from certain.
"We are now in the final moment. We are now really at the moment of truth," UN envoy Espen Barth Eide told reporters in Geneva.
Cypriot President Nicos Anastasiades and Turkish Cypriot leader Mustafa Akinci, who have negotiated for more than 18 months, sat down for around four hours, and were expected to meet again in the evening.
Eide said the Geneva talks had made a good start, but acknowledged that while most issues had been resolved, some of "the most complicated or most emotional issues" remained.
"This is going to be difficult," he said.
But he added: "It is possible... I don't know any issue in these negotiations that really can not be solved if sufficient will is available."
This is the third time the Cypriot leaders have met in Switzerland since November. The previous round broke up with the rival sides saying they remained too far apart on key elements, and blaming each other for the lack of progress.
In the latest round, the leaders are to meet for three days to pore over a range of difficult topics, and by Wednesday they should be ready to provide maps of their proposals for the internal boundaries of a future bi-zonal federation on the eastern Mediterranean island.
If that goes to plan, they will be joined from Thursday by representatives of the island's three guarantor powers -- former colonial ruler Britain, Greece and Turkey.
Turkish President Recep Tayyip Erdogan and Greek Prime Minister Alexis Tsipras are expected to attend, while Britain will reportedly be represented by Foreign Secretary Boris Johnson.
European Commission chief Jean-Claude Juncker is also planning to attend as an observer, his spokesman said.
Both sides acknowledge key issues still need to be thrashed out, with the prospects of solving one of the world's longest-running geopolitical disputes remaining murky.
- Disaster waiting to happen? -
Some experts believe the talks are a disaster waiting to happen because of deep divisions on core issues such as property, territorial adjustments and security.
The two Cypriot leaders have voiced cautious optimism.
Akinci on Sunday described the talks as a "crossroads", while Anastasiades tweeted that he was heading to Geneva "with hope, confidence and unity".
Cyprus, home to around one million people, has been divided since 1974, when Turkish troops invaded in response to an Athens-inspired coup seeking union with Greece.
Nine years later, Turkish Cypriot leaders declared a breakaway state in the north which is recognised only by Ankara.
The years of communal violence, which culminated in the Turkish invasion, saw tens of thousands flee their homes -- and they remain displaced to this day.
Eide pointed to the positive impact success in Cyprus could have in a region wracked with conflicts and political turmoil.
German Foreign Minister Frank-Walter Steinmeier agreed.
"If there is a breakthrough, it would be great news, not only for the people of Cyprus but for all of Europe and the region," he said in a statement.
- Crunch issues -
It has always been agreed that some of the territory currently controlled by the Turkish Cypriots will be ceded to Greek Cypriot control in any deal.
Just how much and which land they should give up has hampered four decades of talks.
The issue is vital because the two leaders have pledged to put any deal to the vote in their respective communities.
In 2004, a majority of Turkish Cypriots backed a UN reunification plan but it was overwhelmingly rejected by Greek Cypriots.
Cyprus then joined the European Union, although EU legislation is suspended in the north until a settlement is reached.
On Monday, the two sides mainly discussed the thorny issue of property.
They have until now remained far apart on how many Greek Cypriots should be able to return to homes they fled in 1974, with Akinci determined to minimise the number of Turkish Cypriots who would be displaced for a second time.
There are still significant differences over security, with Anastasiades wanting Turkish troops to leave the island but Akinci determined to keep a military presence.
Cyprus is often described as one of the most militarised places on earth with the presence of UN peacekeepers, Turkish troops, two sovereign British bases and a Greek army contingent.
Akinci also insists on a rotating presidency with a Turkish Cypriot elected every two years -- a proposal unpopular among Greek Cypriots.