The killings of 27 men in Australia between 1976 and 2000 were most likely homophobic hate crimes, police say.

A New South Wales police taskforce has spent three years reviewing 86 cases in Australia's most populous state.

It was prompted by a report from the Australian Institute of Criminology that questioned whether police had investigated some cases sufficiently.

On Wednesday, police acknowledged that they had previously played a part in "marginalising" the LGBT community.

"[New South Wales Police] acknowledges without qualification both its and society's acceptance of gay bashings and shocking violence directed at gay men, and the LGBT community between 1976 and 2000," it said in a statement.

It added: "There were certainly people murdered because of their sexuality during this time."

'Brutal' violence
The review, launched in 2015, focused on the suspicious deaths of people with connections to the LGBT community.

It found that hate crimes were either confirmed or suspected in 27 deaths, and that further investigation was needed in another 25 cases. Hate crimes were ruled out in 34 deaths.

The report said the level of violence directed towards gay men during the period was "extreme and often brutal".

In some cases, men were found dead in parks and at the bottom of cliffs near known gay beats in Sydney.

"Anti-gay sentiment is very, very difficult to identify from archived files," said Assistant Commissioner Tony Crandell on Wednesday.

However, he said society and police had effectively given attackers a "licence" to target gay people. Homosexuality was only decriminalised in New South Wales in 1984.

Earlier this year, police formally apologised for violence directed towards participants in Sydney's first Mardi Gras in 1978.