The United Nations will call a new summit between leaders of ethnically split Cyprus in January to prod flagging peace talks after a two-day meeting failed to score a substantial breakthrough, a source close to talks said on Monday.

Secretary-General Ban Ki-moon, who oversaw a large part of negotiations in Long Island on Sunday and Monday, was expected on Tuesday to announce a new meeting in mid-January to assess progress, the source said, speaking on condition of anonymity.

The United Nations has been trying for years to reunite Cyprus, the Mediterranean island split between its Greek and Turkish Cypriot populations in 1974 after a brief Greek inspired coup. The present round of peace talks started in 2008.

Although the sides agree in principle to unite Cyprus under a federal umbrella, there are deep disputes on how to co-govern, territorial adjustments between two future constituent states and the property claims of thousands of internally displaced people.

Sources say of particular difficulty were different interpretations of executive rule. Greek Cypriots have proposed rotating presidency under a cross and weighted voting system, while Turkish Cypriots advocate rotating presidency with a separate ballot for each ethnic group.

There has not been a substantive change in positions, the source said, referring not only to the executive question but also issues relating to property rights of displaced persons and territorial adjustments to facilitate a federation.

Cyprus is home to one of the world's oldest U.N. peacekeeping forces, which polices a buffer zone splitting the island East to West.

The south of the island is populated by Greek Cypriots, who represent the island internationally, and the north by Turkish Cypriots who run a breakaway state only recognized by Turkey.

The seeds of division were sown in the 1960s, when Turkish Cypriots left a power-sharing administration amid a constitutional crisis, just three years after independence from Britain.

The conflict has since bedevilled Turkey's attempts to join the European Union, where an internationally recognized Greek Cypriot government represents the whole island in the bloc.

It has been thrown into sharper focus this year after Greek Cypriots launched exploratory drilling for gas off its southern shores. Turkey says the move will harm peace talks and says that any potential hydrocarbon wealth belongs to both communities on the island.

Greek Cypriots counter it is their sovereign right to explore for hydrocarbons, and imminently plan a new licensing round to auction off exploration plots south of the island. The move, in which Russian and French companies will reportedly be given precedence, is seen as an attempt by Cyprus to buffer itself from any potential Turkish claims in the area.

(Editing by Sandra Maler)