Nearly a dozen pipe bombs, some already detonated, have been found on footpaths and in parks in Canberra, sparking a major police investigation and warnings not to touch the potentially explosive items.

ACT Policing detective acting inspector Anna Wronski said the finds were being taken extremely seriously, and police did not know where the pipe bombs had come from or who was behind them.

She urged anyone who found one of the silver tube-shaped objects not to touch it, but to stay nearby and call emergency services.

“We do not want members of the public to pick them up. We do not want members of the public to bring them to police stations. We want them to call triple zero immediately,” Wronski said on Thursday.

As of Thursday morning, 11 pipe bombs had been found along a one-kilometre stretch of footpath near Lake Ginninderra in Canberra’s north-west.

The first was discovered by a passerby.

Some have been found intact in the past two days, while others appear to have gone off before being found.

“A number of the devices have been located intact, and a number have been located partially destroyed,” Wronski said.

Police don’t believe anyone was hurt when the explosives detonated.

Wronski said it was unclear how long the pipe bombs had been there before being discovered, and it was remained unknown whether more would be found.

“Any explosive is dangerous. That’s why we’re taking it so seriously. An explosive in a public place does raise a lot of concern for police,” she said.

Images of the bombs distributed by ACT Policing show a silver piece of pipe with a cap screwed onto the top and bottom.

In one of the images, what could be a fuse extends out of one of the caps.

Wronski said the discoveries were not being treated as terrorism.

-AAP