ALGIERS: The United Nations will restart talks with Libya's rival factions to address outstanding hurdles to a unity government, giving priority to security issues, the new U.N. envoy for the country said Tuesday.

A year of U.N.-sponsored negotiations have so far failed to reach agreement on a proposed national government to end the turmoil in the North African country, four years after the uprising that ousted Moammar Gadhafi as leader.

Libya has slipped deeper into chaos with two rival governments, each backed by a multitude of armed factions. Western governments worry the mayhem has allowed ISIS to gain a foothold there.

Moderates on both sides have agreed to the unity government proposal, as have some of the armed factions. But hardliners in both camps are holding out against the deal.

"Continuity of the dialogue process and building on what has been achieved to date is the way forward," said German diplomat Martin Kobler, who formally took over from Spaniard Bernardino Leon on Tuesday as the U.N. Libya envoy.

He said in a statement he would meet negotiators and members of a U.N.-proposed presidency council that will become the executive of any power-sharing government. Talks on security-related issues would be a priority.

Kobler is an experienced U.N. official who has held top posts in Iraq and the Democratic Republic of Congo.