One of Bristol's busiest commuter roads will be closed from next week for essential safety work to be carried out.

The council announced last night that Bridge Valley Road in Clifton would be closed for "several weeks" from Monday – and it could remain partly closed for about four months.

Diversions will be put in place but will direct traffic onto roads that are already very busy during rush hour.

The closure is necessary for work to be done on the retaining wall above the road, which links Clifton Down at the top of the Avon Gorge with the Portway at the bottom.

The latest monitoring results have revealed that there has been a significant acceleration in the outward movement of the wall, leading to concerns about its stability. The council says the wall needs to be reduced in height.

Officers have scheduled four months for the work to be carried out. The full closure will be in place for several weeks until the wall has been reduced in height, but the road will then be reopened to single file traffic if possible.

Diversions from the north will take motorists along Canford Lane, Sylvan Way and the Portway; diversions from Redland or Cotham will divert to Whiteladies Road and diversions from the south will take drivers to Jacobs Wells Road and the Portway.

Warwick Hulme, managing director of Rubicon Classic Enterprises, which runs the City Sightseeing service, claims no warning was given by the council.

He says the company has had 140,000 new timetables printed for the launch of the new season this weekend.

Mr Hulme said: "The closure means our timetable will be totally up in the air.

"Tourists will also miss out on one of the most spectacular views of the Suspension Bridge."

He added: "This is going to cause traffic chaos."

The council's strategic director, David Bishop, said: "The council wishes to apologise for the disruption that will be caused."