International diplomats are set to join the rival leaders of ethnically split Cyprus for talks that the UN says are the best chance to reunify the island after four decades of division.
UK Foreign Secretary Boris Johnson and his Greek and Turkish counterparts will be in Geneva to discuss security.
The goal is for the two sides to share power in a two-state federation.
Greek Cypriot and Turkish Cypriot leaders on Wednesday exchanged maps proposing territorial boundaries.
It was the first time they had done so, according to the UN, and was hailed as an important advance on the path towards a deal.
New UN Secretary General Antonio Guterres is attending the talks in Geneva, his first foreign trip in the role.
Cyprus has been split since Turkish troops invaded in 1974 following a coup by Greek Cypriots backed by Athens.
Turkey still has 30,000 troops stationed in the island's north.
Britain, Turkey and Greece are the guarantor of Cyprus's independence, which means they can step in if necessary to restore constitutional order.