A 13-year-old boy wearing a hard hat allegedly stole a loader and triggered a low-speed police pursuit across Christchurch.

Witnesses reported several police cars trailing the front-end loader at speeds of about 30kmh before the boy stopped of his own accord more than 10 kilometres from where the machine was taken.

He is understood to have been in Child, Youth and Family care and is well known to police.

The loader, belonging to Taggart Earthmoving Ltd, was taken from a construction site on Langdons Rd in Papanui on Saturday night.

Police were alerted to the theft by a member of the public who saw the loader driving down the road.

It was found abandoned on Vanguard Drive, off Buchanans Rd.

Taggart yard manager Gary Johnson said he received a call from police about 10.30pm informing him of the incident.

He was on his way to pick the loader up, when it was taken a second time by the same boy, triggering a police pursuit which ended in Karnak Cres in Russley.

Johnson said the boy had used a house key to start the loader's engine.

"He's rammed the key into the ignition . . . and played around with it until it's [started]."

Tyre marks at the site gate showed the loader had travelled toward, but not past, the Papanui police station, Johnson said.

"He did very well to get as far as he did without being seen by any police officer."

A witness said he saw the loader "cruise past" down Yaldhurst Rd and turn onto Withells Rd.

"I saw five police cars after him, then a few more followed close behind, and a few more once I went back inside my house."

One passer-by, who wished to remain anonymous, said she saw a large orange loader travelling along Johns Rd at about 11.30pm.

She and her boyfriend were able to follow it for some distance before it turned right on to Yaldhurst Rd.

She said she saw eight police cars pursue the loader, before it turned a sharp left into a residential area.

"We lost it for a while and then found it pulled up surrounded by police. People were running out of their houses to see what was going on."

The passer-by said she pulled over and walked up to the scene and saw a "very young-looking guy aged 12-14 years old sitting in the back of a police car".

"You could barely see him because he looked so small.

"He was wearing a hard hat while operating the [loader].

"It was the funniest thing I have seen in a long time, yet we were a little nervous for police cars."

She said the digger was going about 25-30kmh when the police were able to surround it.

"The guy was too young for a licence for one. We didn't see him break any road rules apart from [driving] in the middle of the two lanes." Johnson returned the loader to the construction site, where work would resume as normal after the Easter break.

The machine had not been damaged in the incident but it was a "major hassle", he said.

"Nobody's been injured, which is a blessing for everybody."

Johnson said police told him the boy may not face charges because of his young age.

A police spokesman confirmed police were called to an incident on Saturday night where a loader was stolen.

"They followed the loader at low speed until the offender stopped the vehicle of his own accord and was spoken to by police."

The spokesman said he was unable to provide further information about the incident without speaking to staff who attended.