Repairs needed for clusters of rocks in danger of falling have closed the Northbound lanes of the Claremont Access until at least Wednesday, the city says.

The city first announced the need for "urgent" repairs to the slope on Friday, and at that time expected the work would only take part of the day.

The lanes are closed from Upper James Street at Inverness to Victoria Avenue South at Main while workers continue to assess and fix the problem.

"It's the nature of the beast, in a way," said operations manager Brian Hughes.

The problem was discovered about a week or so ago, when a contractor was on-site to remove trees in the area that could cause problems.

While removing the trees, the contractor discovered rocks and pieces of concrete that were in danger of falling. The problem was found near the area where there was a wall collapse in 2012, he said.

On Saturday, additional inspection from a consulting engineer found other areas of concern, and so the closure was extended until at least the end of the day on Wednesday.