Hazardous conditions caused by poor weather have delayed clearing slips in the Manawatu Gorge.
The Transport Agency said an extra 2000 cubic metres of rock came down on the road at the weekend.
Some of the new material was cleared, but the risk of further slips with rain forecast made it unsafe to continue.
The agency said it would resume work as soon as possible.
It advised drivers to use Saddle Road or the Pahiatua Track as alternative routes while the gorge was closed.
Manawatu Gorge is prone to slips and was closed for over a year in 2011 and 2012 after massive landslips pushed 375,000 cubic metres of debris over the road and damaged several bridges.
More recently, smaller slips closed the road for a month in 2015.