Australian Liberal MP Malcolm Turnbull has begun polling his constituents on the issue of marriage equality.

The former opposition leader has sent questionnaires to residents in his Sydney seat of Wentworth.

According to the Herald Sun, he said that 68 per cent of 1,800 people who had responded supported gay marriage.

“This survey is important as community views on marriage and the legal status of same-sex relationships are rapidly changing,” he said.

Last November, the Green Party won a motion calling on MPs to ask their constituents about the issue.

Recent polls are showing increased support for a change in the law.

Before Christmas, Fairfax-Neilsen research found that 57 per cent of 1,400 were in favour of gay marriage, while a poll carried out for gay rights groups in October found that 62 per cent were in favour.

The Labor party will debate its policy on gay marriage at its conference this year. Prime minister Julia Gillard has said she believes marriage should be between a man and a woman.