A section of Papaiti Rd north of Wanganui could be closed for about a fortnight after overnight rain brought more earth down on to the roadway.
The first slip occurred about 7.30am on Wednesday when about 5000 cubic metres of soil covered a kilometre-long stretch of the road near its junction with Kauarapaoa Rd.
Workmen had been clearing that slip and had made it passable to four-wheel drive vehicles by Wednesday afternoon. However, it was found yesterday that much more soil had slipped on to the roadway overnight.
Mark Hughes, Wanganui District Council infrastructure manager, said the hill where the slip had come from was now very unstable and the road would be closed to the general public.
"We have informed emergency services that access is not available through the slip. It's likely to be up to two weeks before the road reopens to the public," Mr Hughes said.