State Highway 1 is closed after a serious crash near Warkworth, with authorities warning of significant delays.

Police said emergency services were called to a serious crash on State Highway 1, about 3km south of Warkworth, shortly after noon.

Four vehicles were involved and two people were injured - one serious, one moderate.

Traffic control has been put in place and the Serious Crash Unit advised.

NZTA is asking drivers to use SH16 as an alternative route.

Advertisement

Motorists are being told to expect delays of up to 45 minutes.

"A serious #crash near the intersection with Satellite Station Road is BLOCKING the road in both directions. Emergency services are on site directing traffic. Please expect significant delays" NZTA said on Twitter.

More to come.