Saudi Arabia has expanded a buffer zone along its northern border with Iraq, where a US-led military coalition is bombing ISIL extremists, official media said on Tuesday.

Saudi Arabia has expanded a buffer zone along its northern border with Iraq, where a US-led military coalition is bombing ISIL extremists, official media said on Tuesday.

Mohammed al-Fahimi, a spokesman for northern region border guards, said "the depth of the border has been increased by 20 kilometers (12 miles)", the Saudi Press Agency reported.

Officers guarding the frontier "called on residents and citizens to stay away from the border areas", it added, without clarifying the previous depth of the border zone.

In early September, the kingdom inaugurated a multilayered fence, backed by radar and other surveillance tools, along its northern borders.

The project is part of efforts to secure the kingdom's desert frontiers against infiltrators and smugglers, state media reported at the time.

Saudi Arabia shares a boundary of 800 kilometers with Iraq.