Two suspicious packages that were found at Gower Park last week.

An item made of metal piping with protruding wires placed under the bowl of a public toilet is the latest in a string of suspicious items requiring bomb squad action in Hamilton.

In the last six months the Auckland-based bomb squad has been called in to deal with four suspicious items located in different public locations around the city.

Last Thursday the central city shopping mall was evacuated for almost four hours after a suspicious package was delivered to the ANZ Bank at Centre Place.

Bruce Mercer Auckland's Defence Force team set up a robot at Gower Park, Hamilton, where a suspicious package was found this morning.

The latest incident on Monday involved an unusual piece of metal piping police say was purposely made to look like an explosive device and placed in the toilet block at the park in Hamilton Lake area.

Hamilton police Senior Sergeant Neil Faulkner said police received a call from Hamilton City Council staff who found a suspicious item in the women's toilet about 8.30am Monday.

"It was described as being a pipe with wires coming out of it, placed underneath one of the toilet bowls in the women's toilet."

Police set up a 200 metre cordon around the toilet block on the Sandleigh Rd side of the park, below Waikato Hospital, and halted motorists and pedestrians entering via Hibiscus Ave.

Residents of about 10 houses in the cul-du-sac on Sandleigh Rd were told to stay inside their homes while the Auckland-based Defence Force team dealt with the item.

"It is the normal operating procedure when dealing with a suspicious package until the defence force have assessed it," said Faulkner.

"We make an assessment of the information that we have and decided to get the Defence Force to neutralise the item."

The bomb squad team arrived in a white van at the quiet park, lined with hospital workers' cars about 11am. About 20 minutes later a robot was deployed from the rear of the van into the building where the item was located in a small stall.

"They have tried to use the robot to go in there with cameras to take a look at the device and neutralise it if needed," said Faulkner.

"However, due to the close proximity of the walls and the cubicle they were unable to manoeuvre it sufficiently so they have done a manual approach."

One of the senior bomb squad members adorned in a specialist protective suit was sent into the cubicle to manually neutralise the item, said Faulkner.

"They are a specialist unit and luckily we had one of the main guys who was able to deal with it. They have a device that fires a water shot through it and blows it to pieces basically."

"We had a number of other contingencies here - fire and gas - in case something eventuated that was outside of our control."

Maddie Cambort was visiting friends on Sandleigh Rd when she heard a loud bang about 12.15pm.

"It was really, really loud, sounded like a gunshot wound. The glass shook a little."

Faulkner said the item, which was being investigated by Waikato CIB, had been purposely made to look suspicious.

"It was made to look like an IED - Improvised Explosive Device - but initial thoughts from the Defence Force are that it probably is not going to cause any danger to the public as it was."

Hamilton City Council Parks and Open Spaces Manager Sally Sheedy said the toilet blocks were open from 7.30am to 7.30pm daily. Outside of those hours only authorised council staff had access.

The item had likely been placed in the toilet sometime between Sunday morning and Monday, said Faulkner.

"It was there this morning, so it could have been anytime between when it was cleaned [Sunday] and when the doors were locked last night."

The bomb squad had recently used the robot to destroy a suspicious bag that had been found abandoned in the Hamilton IRD building on Bryce St. Police later tracked down the owner of the small blue bag left in the foyer who said she had forgotten she left it there.

Back in December the bomb squad were again called in to deal with a suspicious item discovered outside Davies Medical Centre on Hukanui Rd.

University of Waikato political scientist Dr Colm McKeogh said there was a heightened sensitivity to security threats in today's climate.

"There's been two bomb scares in Hamilton, the IRD, which turned out to be innocuous and Centre Place and the one today is either a bomb scare or a threat. We don't know yet."

"Plus there's been the 1080 milk powder threat and the Lindt Café in Sydney..[which] brought it much closer to home the possibility that it could happen here."

The response from the Defence Force and police was sometimes inconvenient for residents, but warranted in all cases due to what was happening with the Islamic State and the recent domestic threats made to milk powder, he said.

"The Defence Force is more aware of bomb scares in New Zealand and there's good grounds. At the moment they have to take them seriously because of what's happening nationally and internationally."

"It's a safe place (Hamilton) but it takes only one incident to shatter that belief."

Police said all three recent events are being treated as unrelated and all items were assessed as not being dangerous.