Prime Minister Malcolm Turnbull says Coalition MPs will be free to ignore the result of the public vote on same-sex marriage and follow their consciences after the national plebiscite.

Mr Turnbull said that when it comes to legislating change he would not bind his cabinet colleagues to vote according to the will of the people, but that he expected most MPs – including those opposed to same-sex marriage – to accept the public's verdict.

The details of the proposed plebiscite, including the exact question to be asked, have yet to be resolved even though a vote is expected by the end of the year. It has been unclear whether Coalition MPs, particularly cabinet members, would be forced to accept the plebiscite verdict.