Gay plebiscite frustrating but needed: PM

Malcolm Turnbull admits it's frustrating for same-sex marriage supporters to wait for a plebiscite.

The prime minister said the public vote option was not "the traditional way of resolving matters" in Australia but it was preferred by coalition MPs before he took office.

"I can understand it's frustrating for people who want to get on with it, and obviously it has a cost," he told Hobart radio 7HO, adding he'd vote in favour of legalising gay marriage.