More than 80 same-sex couples, including 24 from overseas, have said "I do" in New Zealand since a law legalising gay marriage took effect a month ago, figures showed Friday.

Officials expect the number to accelerate as New Zealand moves from the gloom of winter into the more desirable wedding months of spring and summer.

Since August 19, when New Zealand became only the 14th nation in the world, and the first in the Asia-Pacific, to legalise same-sex marriage, there have been 82 gay marriages, the registrar-general of births, deaths and marriages, Jeff Montgomery, said in a statement.

"We are seeing continued national and international interest by same-sex couples in getting married in New Zealand," he said.

"We expect the number of same-sex weddings to increase as we move into spring."

Of the 82 weddings, 42 were female and 40 male.

The 24 overseas same-sex couples who have travelled to New Zealand to get married included 13 from Australia, four from Thailand, three from China and one each from Hong Kong, Britain and the United States as well as a Filipino-American couple.

New Zealand decriminalised homosexuality in 1986 and approved same-sex civil unions in 2005.