Police investigating the reported abduction of a Timaru boy have spoken with a woman who told media she'd seen a suspicious man photographing children at Oceanview Heights School.

Mid-South Canterbury Area Commander Dave Gaskin said the woman, identified in media reports as 52-year-old Catherine Sadler, had been interviewed, but he did not disclose what information she had provided.

Gaskin said he didn't yet know if she had given a description of the man she saw and cautioned that it was not known if the information was relevant to the investigation.

Meanwhile, two officers are hoping to speak again this afternoon with the nine-year-old who was apparently abducted and assaulted on Thursday after leaving the school.

The boy remains in Timaru Hospital in stable condition with injuries to his mouth and jaw.

He was found at Holme Station Bridge at 4.20pm on Thursday, after leaving Oceanview Heights School in Selwyn St about 3pm.

Investigators first spoke with the boy yesterday in a "preliminary interview ... (to establish) rapport with the young man," Gaskin said.

"Interviewing children is always a difficult task and it's going to take time to get the truth as to exactly what happened."

The boy's injuries did not prevent him from talking, and he did engage with police, Gaskin said.

Gaskin would not say whether any persons of interest had been established, or confirm whether police believed the abduction was sexually motivated.

Police were "slowly but surely" building a picture of what happened from information gathered from the public, he said, but would not elaborate.

The investigation has put additional strain on the already-stretched resources of Timaru's criminal investigation staff. The department is handling several serious crime investigations that have occurred in recent months.

Staff have been pulled from other investigations to focus on the abduction case, Gaskin said.

He said he had not requested additional assistance from Christchurch, aside from enlisting the help of a team specialising in crime scene searches that combed the Holme Station Bridge area at the weekend.

Gaskin urged anyone that had information to call the Timaru police on (03) 687 9808 or to visit the police station in North Street.

- © Fairfax NZ News