A desperate mother is begging for help to punish her 11-year-old son, who has admitted ransacking graves and starting a fire in a $300,000 spree of destruction with a mate.

The Masterton woman, who cannot be named for legal reasons, broke down in tears while speaking about her boy, who has an attention deficit disorder, and her loss as to make right "the terrible things he's done".

She said she was "really scared of the lines he's going to cross next".

"I'm at the end of my rope. I don't know what to do with him. I really need help," the solo mother said. "I've grounded him but I don't know what else to do.

"It's the community he's hurt, so I need suggestions from the community about any reasonable punishment I should give him.

"And I'm not talking light punishment here - he needs to take things to heart and it's got to stick so he never forgets it."

The woman said the first she knew of her son's involvement in the massive blaze on Saturday that caused hundreds of thousands of dollars worth of damage was when he told her there was black smoke in the sky.

"He asked if he could go and look at it, and next thing the dog handler's at my door asking about my boy and my cellphone, which he'd used to call the Fire Service a couple of minutes after they lit the fire."

The boy and his mate set the blaze shortly before 6.30pm at a recycling depot at the Masterton rubbish transfer station. The flames destroyed a large shed full of baled cardboard and 200 new recycling bins.

The fire rapidly spread and destroyed a front-end loader, believed to be worth $150,000.

Firefighters, who were at first hampered by a lack of water, took three hours to bring the inferno under control.

The boys had earlier ransacked nearby Riverside Cemetery, smashing headstones, ornaments, flower pots and planters.

Police estimated the cost of the vandalism and arson was at more than $300,000.

The boys have been referred to youth aid and will face a family group conference.

A Masterton police spokesman said that from there, conditions would be imposed on the boys, but they were not criminally liable for their actions because of their age.

The mother said the boy had seen his father only a handful of times in his life and she blamed lack of a male role model in the home as a contributing factor in his wild behaviour.

She said her son routinely breached her 6.30pm curfew to be back at their home, which is smoke-free and smack-free. "I let him take the cellphone so we can keep in touch but sometimes he's out until 11 or 12 at night. The other night it was even later."

She said he was pulled out of school last year after a violent incident involving other children and spent time on a course for youngsters who were hard to handle.

The mother said she was most devastated by the "absolute disrespect" her son had shown during the attack on the cemetery.

"I can't believe he did that - respect for the dead was something I thought I'd really drilled into him."

The woman believes any punishment should include forcing her son to clear up the damage at the cemetery and to help keep it tidy "for at least three months".

"Something like that might have an effect on him as well as making some good on the harm he's done. I love my boy - that will never stop - but right now I really don't like some of the things he's doing."

This week, another Masterton resident told the Herald the boy and his mate were known troublemakers and vandals.

- APN, staff reporter