The New Brunswick government has passed new legislation that will make booster seats in vehicles mandatory for small children as of May 1.

Children younger than nine will have to be strapped into a booster seat with a seatbelt until they weigh 36 kilograms and are 145 centimetres tall (79 pounds and four feet nine).

"In a collision, a child restrained only in a seatbelt, and not a booster seat, is 3½ times more likely to suffer serious injuries, and four times more likely to suffer a head injury," said John Foran, the province's minister of public safety.

"So we feel this is a very important measure that will greatly improve the safety of our children."

The move is part of the government's promise during the last election campaign to tighten safety rules, Foran said.

"The premier had campaigned on this as we all did, and highway safety is a priority of our government," Foran said.

New Brunswick is the fifth province to make booster seats mandatory. Ontario, Quebec, Nova Scotia and most recently British Columbia have all rewritten their booster seat regulations.

A promotional campaign will be launched in New Brunswick in the new year to let parents know about the new rules.