A father of five from Vancouver is speaking out after being told his children can't ride public transit together without adult supervision.

Adrian Crook used to send his four oldest kids, who range in age from seven to 11, on a city bus from downtown Vancouver to their school on the North Shore every morning. The 13-kilometre trip took them 30 minutes, and they always carried a cellphone with them.

"This was a thing that I planned for a while," Crook said. "I sold our car and I talked to TransLink to make sure there was no minimum age, and they informed me that it was a parental discretion issue."

For the first year, Crook or a caregiver would ride along with the children at least part of the way to school, but in the spring he decided it was time to send them off on their own.

"There was never a single issue," Crook said.

But that came to a halt when B.C.'s Ministry of Children and Family Development received an anonymous complaint that his kids were unsupervised.

The ministry launched an investigation, and had Crook sign a safety plan requiring that he ride the bus with his kids until the probe was completed. In the end, the province ruled his kids required supervision.

Crook, who runs a blog on parenting called 5 Kids 1 Condo, said he was told children under 10 should not take the bus – or go anywhere outside the home – at any time of day without adult accompaniment.

"Now they can't even go to 7-Eleven, which is across the street," he said. "When they're at their mom's house and only a few blocks from school, they can't even walk to school on their own. So there are a bunch of their peers doing that can do things that they can't do anymore."

According to Dr. Mariana Brussoni, a developmental psychologist with the University of British Columbia, the ministry's decisions aren't always based on the best available evidence.

Some parents' fears about letting children make their own way to school are overblown, Brussoni added, particularly concerns about stranger danger.

"It's never been a safer time to be a child in Canada than it is now. The likelihood of getting kidnapped by a stranger is one in 14 million," she said.

"And yet the leading cause of death for kids is kids in cars. Parents, in their misguided effort to keep kids safe, are putting them in cars and driving them places, not understanding that they're putting them at greater risk."

Between 2009 and 2013, 106 Canadian children died in private vehicles. None died on buses over the same time frame.

Crook, who also runs a design consulting business, is complying with the ministry's order, but he's also raising money to challenge the government in court.

"It's the safest mode of travel, buses," Crook said. "I was choosing a safe option. And we need, as parents, to be allowed to make those choices for our kids, especially if nothing has gone wrong."

A spokesperson for the Ministry of Children told CTV News he couldn't comment on the specifics of the case, but said staff respond to complaints by considering a number of factors, including the children's maturity and comfort level.

"If social workers determine there is a risk to a child or to children, their first step is to immediately reduce that risk," he said in an email.

With a report from CTV Vancouver's Jon Woodward