Police were alerted to a sudden death about 11.30am.
Detective Senior Sergeant Mike Hayward said that while carrying out investigations at the scene, police located a suspicious item near the body.
The object was first thought to be an improvised explosive device (IED).
"The area was immediately cordoned off, including the closure of SH1 between Princes Street and Highbrook Drive," Hayward said.
The Police Specialist Search Group and the NZDF EOD Team were sent to the area. After a thorough search two objects were found, both of which were safely removed from the scene.
"Initial enquiries indicate that these items are not IEDs, and further specialist enquiries will need to be carried out into these two objects."
The southbound lanes on SH1 reopened about 3pm.
Hayward said there were no immediate concerns for anyone's safety and police will remain in the area.
A scene examination was under way and likely to continue into Wednesday.
Police will carry out inquiries into the man's death on behalf of the Coroner.
