Same-sex couples in Australia have tied the knot on the first official day of ceremonies following the passage of a historic law.

Although some couples wedded last month after obtaining special exemptions, most could not marry until today.

Australian athletes 23-year old Luke Sullivan and 29-year old Craig Burns, exchanged vows and a kiss just after midnight in a small ceremony in new South Wales.

The beaming pair celebrated with fireworks.

Mr Sullivan said he had been overwhelmed with messages of support.

He told the Australian Broadcasting Corporation that his instagram direct messages have blown up with people he has never met, just sending love and congratulatory messages.

Sullivan married his partner Burns, a sprinter who competed in the Glasgow Commonwealth Games, in front of about 50 family and friends.

In Melbourne, Diana and Deanne Ribeiro wedded a minute after midnight, in the same place where they held a commitment ceremony five years ago.

The Australian parliament made same-sex marriage legal last month, following a national survey that showed support from 61 percent of voters.

A one-month registration period was waived for some couples with special circumstances, meaning they could wed before today.

Australia now joins more than 20 other nations in allowing same-sex weddings.