A United Nations envoy urged Lebanon’s feuding political leaders to pick a new president.

A United Nations envoy urged Lebanon's feuding political leaders to pick a new president, warning on Monday that the country's year-long power vacuum had undermined its ability to deal with the impact of the Syrian crisis and a host of other problems.

The presidency has been vacant since May 2014 because lawmakers cannot agree on a candidate.

"I urge Lebanon's leaders ... to put national interests above partisan politics for the sake of Lebanon's stability, and to show the flexibility and sense of urgency needed to resolve this issue," UN Special Coordinator for Lebanon Sigrid Kaag said in a statement marking one year without a president.

She said the vacuum had hindered the country's ability to tackle growing security, economic and social problems.

"It has contributed to political polarization at a time when Lebanon must make a united effort to safeguard the country from the impact of the Syrian crisis," she said.

The presidency has fallen victim to political deadlock rooted in Lebanese rivalries that have been complicated by the interference of foreign states, notably Saudi Arabia.