Hobart City Council will fly the rainbow pride flag until same-sex marriage is legalised.

The council has voted to fly the LGBTI community’s flag on the HCC building as part of its social inclusion strategy, which has been in place since 2014.

“Hobart City Council has always had a huge social conscience and we've exhibited that on a numerous occasions,” Lord Mayor Sue Hickey said.

“We've also written as a council, all 12 of us, to the Prime Minister asking for a push for marriage equality as soon as possible.

“We want to signify that the Hobart City Council is very supportive of social inclusion.”

Alderman Hickey said flying the flag was latest in a number of pro-marriage equality measures, following a unanimous vote in 2015 to support same-sex marriage.

“It's very much about the social inclusion strategy,” she said.

“We'd just like to focus on the fundamental right of every individual to have an opportunity to participate equally whether it's socially, culturally, economically, physically or politically in society.

“We just don't believe in excluding someone based on their sexual orientation.

“I think the general public are horrified that we're going to spend $122 million on a postal vote that's non-binding that could be flawed,” she said.

Alderman Hickey said councils were right to adopt a social agenda.

“We are the third tier of government and we're not just roads, rates and rubbish. We are there for our community, every single one of them,” she said.

“We look after elderly, we look after disability, we look after homelessness, we look after youth at risk, we look after migrants and we look after LGBTI.

“The social inclusion strategy is very much a part of the work we do, and that's what people have got to get into their heads.”