The City of Saint John will seek leave to appeal Justice William Grant's decision last week to certify a class action lawsuit in the Kenneth Estabrooks case.

Estabrooks was a city police officer between 1953 and 1975 when he admitted to superiors he had sexually abused at least two boys.

He was not charged at the time, and was instead transferred to the city works department where he retired in 1983.

An investigation launched by the city in 2012 revealed he may have abused hundreds of youths over a three-decade period.

John McKiggan, the Halifax lawyer representing Robert Hayes, a victim who launched the class action lawsuit against the city on behalf of all children abused by Estabrooks, said the city's decision to appeal is "disappointing but not surprising."

"One would ask, why would the city go to the effort of investigating and reaching out and identifying more than 300 survivors of Estabrooks's abuse if they didn't intend to do anything about that or take any responsibility for that?" he said.

"What was the purpose of that investigation?"

In October 2012, the city engaged a firm, Investigative Solutions Network, to locate victims who had been abused by Estabrooks.

The subsequent report, written by ISN's co-CEO, Dave Perry, reported that as many as 263 youths may have been sexually abused by Estabrooks.

ISN was paid $446,000 for its work.

In his decision Thursday, Justice Grant found the plaintiff, Robert Hayes, "has satisfied the requirement of demonstrating that a class proceeding is the preferable procedure in this case."

The move to seek leave to appeal the certification followed a special closed-doors meeting of council Tuesday.

It was then formally approved in an open meeting with no discussion.

Councillors are not commenting on the decision.

Estabrooks was eventually convicted in 1999 on four charges of indecent assault involving three boys and a girl during the years he worked for the city.

He was sentenced to six years in prison and died in 2005.