The United Nations secretary-general is promising to lend his personal support to rival Cypriot leaders continue to engage in complex talks aimed at reunifying the ethnically divided island nation.

Ban Ki-moon said the U.N. and he will personally do "our utmost" to assist Greek Cypriot President Nicos Anastasiades and breakaway Turkish Cypriot leader Mustafa Akinci reach a peace deal to the decades-old problem.

Ban, who met with both leaders Sunday, called on them to "make the most" of the time ahead to overcome hurdles still impeding an accord.

He said "time is of the essence" and called the period ahead "crucial." Both Anastasiades and Akinci have said they aimed to reach a deal by year's end.

Cyprus was split in 1974 when Turkey invaded after a coup that aimed at union with Greece.