The Lindis Pass is blocked following a serious crash.

A police spokeswoman said it happened about 8:30am 15km from the summit and involved two vehicles.

Motorists are advised to take an alternate route.

NZTA said the serious crash unit is likely to attend this crash, and the road will in all likelihood remain closed for several hours while investigations take place.

Southbound traffic can detour via SH83, SH1, SH85 and back onto SH8.

Reverse is available for northbound traffic.

Allow up to an additional 2 1/2 hours for this detour route.