Personal details of Mr Fluffy-affected homeowners have been leaked by an ACT public servant and have sparked a police investigation, it has been revealed.

The ACT Asbestos Response Taskforce said a public servant gave a communications company a hard copy of the names and addresses of all 1,022 Mr Fluffy homeowners in May or June.

It is believed a hard copy of the list was left in an unmarked envelope at the office of the information and communication technology contractor.

The list was then distributed to a number of employees and contractors at the company with a message reminding them to be cautious when undertaking work at affected homes.

Taskforce head Andrew Kefford has apologised to Mr Fluffy homeowners, and said it is understood the list was only provided to the one company.

A letter went out to affected homeowners this morning.

In July, the taskforce released the full list of the Mr Fluffy-contaminated homes in the capital.

The list identifies — by the block, section and address — where potentially deadly loose-fill asbestos was installed as insulation by the Canberra-based Mr Fluffy company in the 1960s and 1970s.

But the list did not identify personal details of owners.

Company has destroyed unauthorised list of personal details

Today, Mr Kefford said he first became aware of the leak on June 20 and immediately asked ACT Police and the Commissioner for Public Administration to investigate.

"It was recommended we not publicise those investigations at that stage so as not to jeopardise them," he said.

"The taskforce has cooperated fully with the investigations to date, and will continue to do so.

"I'm very angry that it's occurred, I'm disappointed that this has happened and I feel let down that it's happened."

Mr Kefford said the source of the unauthorised release has not yet been confirmed but acknowledges the impact it will have on homeowners.

"Since the taskforce was established, information security has been a key consideration in our work and one which we have taken, and continue to take, seriously," he said.

"Any improvements suggested through the investigation around information security will be implemented."

The Public Administration Commissioner, Bronwen Overton-Clarke, is conducting an investigation along with ACT Policing.

She said the company has destroyed the list and is fully cooperating with the investigation

"It is a breach of people's privacy and that's why we're taking it so seriously," she said.

"Public officials are not allowed to disclose private information in such a way as this, without authority to do so."

Ms Overton-Clarke said the leaked information was an offence under the Crimes Act and the ACT's public service guidelines.