UNITED NATIONS (Reuters) - United Nations chief Antonio Guterres will return to Switzerland to attend talks to reunite Cyprus on Thursday because it is “opportune,” his spokesman said on Wednesday.

United Nations Secretary-General Antonio Guterres attends a news conference with Portugal's Foreign Affairs minister Augusto Santos (not pictured) at the Necessidades Palace in Lisbon, Portugal July 3, 2017. REUTERS/Rafael Marchante

Guterres was in the Swiss resort of Crans-Montana on Friday - on the third day of negotiations - to lend his weight to the effort to unite Cyprus under a federal umbrella.

“The Secretary-General feels that his presence in the talks would be opportune tomorrow. There have been also a number of calls from the parties for him to return,” U.N. spokesman Stephane Dujarric told reporters.

Guterres said on Saturday that a “clear understanding” had been reached at the talks between Greek Cypriot and Turkish Cypriot leaders and their backers on what was needed to reach a comprehensive agreement to reunite the island.

Greek Cypriot leader Nicos Anastasiades said on Wednesday he would submit proposals to overcome a deadlock that had become apparent over the past week of talks.

“I expect that the other side will show the same good will, to move forward,” he said. “We have to deal with these issues seriously to see a glimmer of hope, of light for the future.”

Cyprus was split in a Turkish invasion in 1974, triggered by a brief Greek-inspired coup. Turkey supports a breakaway Turkish Cypriot state in northern Cyprus.

Two issues have proved especially vexing: Turkish Cypriot demands for a rotating presidency, and Greek Cypriot demands that Turkey withdraws all of its 30,000 troops from the island and renounces its intervention rights.

“They’re getting closer but they’re not there yet. If this deal is going to be done it’s going to be done with the Secretary General ... They genuinely have a lot of faith and trust in him,” said a diplomatic source, speaking on condition of anonymity.

“Everybody knows what they have to give but it’s almost as if they’re waiting for the Secretary-General to come back before they show their cards,” said the diplomatic source.