The highway was closed a month ago on October 25 for safety reasons, adding hours to the journeys between Walcha and the Hastings. A Transport For NSW spokesperson said it will remain closed for up to four weeks.

"Work has begun to remove fallen trees and rocks, and to restore damaged guardrails and road surface," said the spokesperson.

"Further, four retaining walls have been extensively damaged and need to be replaced to ensure the safety of road users on the Oxley Highway.

"Transport for NSW will reopen roads as soon as it is safe to do so, but our first priority is the safety of motorists and the community," added the spokesperson.

Transport for NSW has seven teams working on the safety hazards, to reopen the road as soon as it is safe to do so.

Meanwhile, motorists in northwestern NSW will soon enjoy smoother rides along the Oxley and Pacific highways with a resealing program about to begin at multiple locations.

Transport for NSW Director Northern Region Anna Andrews said the NSW Government was investing $1.2 million in the program, which is expected to be complete before Christmas.

"The holidays are a time when we travel long distances to visit family and friends, and Transport for NSW wants to ensure motorists can enjoy safer travel conditions," Ms Andrews said.

"The maintenance work will start on Monday 25 November and is anticipated to be completed before Christmas and the busy holiday travel period."

The work will be carried out on a 20 kilometre section of the Oxley Highway between Long Flat and Mount Seaview and a seven kilometre section of the Pacific Highway north and south of Paddys Rest area.

Traffic will be reduced to one lane within the work sites. A single lane with a reduced speed limit will be in place for the safety of workers and motorists.

Motorists are advised to drive to the conditions, and follow the directions of signs and traffic control.