A section of Auckland’s Southern Motorway is closed due to an “ongoing operation”, police say.

The southbound lanes of State Highway 1 were initially closed between Princes St East and Highbrook Drive in Highbrook.

Just before 1pm the cordons were extended, with the southbound lanes of SH1 closed between Mt Wellington Highway and Highbrook Drive, NZTA wrote on X to “expect delays”.

Police said the incident was occurring in a walkway next to the southbound lanes.

“[The closure] this is out of an abundance of caution for motorists while the operation is carried out.

“Police will provide further details in due course.”

Part of a walkway has been taped off next to the Southern Motorway in Highbrook due to a police operation. Photo / Dean Purcell.

A police officer on a pathway next to a closed section of the Southern Motorway in Highbrook this afternoon. It's not immediately clear what the police operation is for. Photo / Dean Purcell.

Police staff and emergency tape could be seen on the walkway, which is next to upper part of Tāmaki River.

Hato Hone St John said they had two rapid response vehicles on standby.

“No other involvement from us.”

A motorist caught in the traffic described the situation facing motorists.

“It’s gridlocked - standstill.”

Traffic builds up southbound on State Highway 1, Auckland, as a police operation closes off a section of motorway in Highbrook.

Photos taken by motorists show three lanes of traffic being guided off the motorway.

“A detour is available via the Mt Wellington offramp, through Great South Rd and rejoining at Highbrook Drive”, NZTA said.