Gay marriage won't impact on trade: Robb

Trade Minister Andrew Robb says he doesn't think allowing same-sex marriage would harm Australia's trade with regional partners.

"From my observation, social issues tend not to be a factor in a lot of agreements in trade," he told the National Press Club in Canberra on Wednesday.

Agriculture Minister Barnaby Joyce has previously warned Asian countries could see Australia as "decadent" if it change marriage laws.