Heavy rain that hit the West Coast this week has damaged and forced the closure of a rail line between Buller and Ngākawau.

Severe weather hit the area on Monday causing slips and road closures.

A spokesperson for KiwiRail said the rail line suffered "considerable damage".

They said they will be working hard over the coming days to re-open the line which has been washed away in places.

On Monday, two slips also closed off a West Coast highway.

State Highway 6 Punakaiki to Greymouth was closed at Ten Mile and was closed at Lyell between Eight Mile and Inangahua.

The highway was reopened later in the day.

Heavy rain that hit the West Coast this week has damaged and forced the closure of a rail line between Buller and Ngākawau. Photo / Supplied

A heavy rain watch was in place for Buller and Westland from Otira northwards from 9pm on Sunday to 8am on Monday.

MetService warned the period of heavy rain could approach short-duration warning criteria,