GENEVA (AP) — Talks to reunify long-divided Cyprus are on track to overcome major obstacles that have stood in the way of a peace accord for decades, the United Nations envoy for Cyprus said Wednesday.

But an immediate deal won't be in the offing since important legal and technical details will have to be sorted out before an overall agreement is put to a vote to the island's rival Greek and Turkish Cypriot communities, U.N. envoy Espen Barth Eide said.

Eide said the Greek Cypriot president and the Turkish Cypriot leader would present competing maps later in the day that outline the boundaries of the Greek and Turkish zones that would make up the country in a hoped-for federation.

The proposals will be seen by only a handful of people before being placed in a U.N. vault in Geneva, a testament to the delicateness of the diplomatic task, Eide said. Top diplomats from three key countries are poised to join the talks on Thursday.

Greek Cypriot President Nicos Anastasiades and Turkish Cypriot leader Mustafa Akinci have been meeting in Geneva since Monday to discuss a number of outstanding issues that could restore unity to the island split by ethnic divisions for almost 43 years.

Turkey invaded Cyprus in 1974 in response to a coup aiming to unite the island with Greece. Many residents were stripped of homes and property when Cyprus divided into an official Greek Cypriot south and a breakaway Turkish north.

Foreign ministers from Cyprus' three "guarantors" — Greece, Turkey and former colonial power Britain, which has a major military base on the island — are set to join the negotiations on Thursday to discuss post-unification security issues.

Top leaders from the European Union, which counts Cyprus as a member, are also expected.

"I really think, without overdramatizing what is happening in Geneva, that this is the very last chance to see the island being recomposed in a normal way," European Commission President Jean-Claude Juncker told reporters in Malta's capital on Wednesday.

Eide has sought to manage expectations. He has repeatedly pointed to "historic" advances happening at the summit, which is the first time the rival boundary maps will be exchanged and the three guarantor powers will be around the table at such a high-level.

"We are on track," Eide told reporters during a break Wednesday. "We have dealt with some of the most difficult issues. We have touched upon almost all of them, we have solved many of them, and we are close to solving some other issues."

He refused to specify which issues had been resolved, saying some might be more "popular."

The closed-door talks have focused on governance, property and territory issues so far, Eide said.

"There's still work to do," he added.

Eide did not rule out the possibility that British Prime Minister Theresa May, Greek Prime Minister Alexis Tsipras and Turkish President Recep Tayyip Erdogan might attend along with their foreign ministers. But he suggested they would come only if a deal was in hand.

"It's actually quite normal procedure that a topic like this starts at a high political level and when and if successful, it's escalated to the very highest level," he said.

Hadjicostis reported from Nicosia, Cyprus. Raf Casert contributed from Brussels, Belgium.