A crash has closed the southbound lane on State Highway 1 between Hamilton and Auckland on Saturday.

Police report that two vehicles crashed on the expressway near Hampton Downs about 11.20am on Saturday.

NZTA report that the lane is closed between the Hampton Downs Southbound Off-ramp and Hampton Downs Southbound On-ramp.

One person is reported to have serious injuries.

There is a detour in place. Southbound traffic take the Hampton Downs Off-ramp then use the On-ramp to re-join SH1.

Police advise people to avoid the area or delay travelling. Those who are travelling on this route are advised to expect delays and pass the scene with care.

It is unknown when the lane will be unblocked again.