The Turnbull government will push back the date of the proposed same-sex marriage plebiscite until February 2017, breaking a flagship pledge.

The Prime Minister had said he wanted the vote to be held this year.

However a spokesperson for Mr Turnbull told Fairfax Media that Special Minister of State, Scott Ryan, received advice last week from the Australian Electoral Commission (AEC) advising the government to push the vote back.

"The government has always said that a decision on same-sex marriage will be made by a vote of all Australians in a national plebiscite to be held as soon as practicable," the spokesperson said.