Two men in the Western Australian city of Perth have become the first gay couple in Australia to legally adopt a child.

The government has not released the identities of the parents or the child who is believed to be a boy.

According to media reports last Thursday, the adoption - arranged by the West Australian state government - follows 2002 changes to the state adoption Act. The changes allowed same sex couples to adopt a child, said Department of Child Protection's Accommodation and Care Services acting executive director David Vicary.

Western Australia and the Australian Capital Territory are alone among Australia's eight states and territories in allowing same-sex partnerships the same adoption rights as heterosexual couples. Nationwide, however, individuals — gay or straight — have had the right to adopt children for years.

"This was a local WA adoption and the biological parents were fully involved in the selection process for the adoptive parents," Vicary said.

WA Attorney-General Jim McGinty who acknowledged that while some people would find the decision to let a gay couple adopt challenging, he said the child's best interests were considered.

"This is the first time a mother has relinquished a baby for adoption to be taken up by people not related to her and this is the first occasion in which a gay couple have applied for and been deemed to be the most appropriate people from all available to care and love for that child," he said in a statement.

"The only consideration when it comes to adoption is the best interests of the child."

"So long as the child is in a loving, caring relationship I don't think he can ask for much more than that," he said.

The adoption, which attracted strong opposition from church groups and certain quarters of the WA government, is likely to raise the ire of Prime Minister John Howard. His government last year pushed through federal legislation banning gay marriages.

Howard said last week that he opposed gay adoption and that ideally children had a mother and a father as it "gives children the best opportunity in life". His comments were in response to the Victorian Law Reform Commission's recommendation that same-sex couples be allowed to apply for adoption and lesbians have full access to IVF treatment and female partners of biological mothers be recognised as legal parents.

On Monday, members of Parliament voted 51 to 4 against a motion to allow adoption and access to IVF by same-sex couples and single parents.