WASHINGTON (Reuters) - A majority of adoption agencies in the United States are willing to accept applications from homosexuals and lesbians and 40 percent have already placed children with same sex partners, according to a survey to be released on Wednesday.

The study by the Evan B. Donaldson Adoption Institute, funded by the Rainbow Endowment, a group that promotes homosexual rights, was based on a questionnaire mailed to directors of 51 public and 844 private adoption agencies, of which 307 responded.

"The research clearly shows how extensively attitudes in our country are evolving," said Adam Pertman, executive director of the Donaldson Institute.

Homosexual rights is emerging as one of the hottest political issues in the country, highlighted by a recent Supreme Court decision striking down state laws banning homosexual practices in private and the decision by the Episcopalian Church to elevate an openly homosexual man to be Bishop of New Hampshire.

A poll earlier this year by the Pew Research Center found that while a majority of Americans opposed same sex marriage, opposition had been decreasing in recent years from 65 percent in 1996 to 53 percent in 2003.

That study found that opposition was strongest among evangelical Christians and blacks but was dropping among Catholics and mainline Protestant sects such as the Lutherans and Episcopalians.

The adoption survey found that religious affiliation or the lack thereof was a key factor determining whether or not an adoption agency was willing to work with homosexual couples.

About one fifth of responding agencies said they openly recruited homosexual adoptive couples by advertising they were "gay friendly."

The types of agencies most willing to place children with same sex parents were public, secular private and Jewish and Lutheran-affiliated agencies. Baptist-affiliated agencies refused to work with same sex couples, as did most Mormon and Catholic-affiliated adoption agencies.

Almost three quarters of agencies said they asked about the sexual orientation of the prospective parents during the vetting process. One quarter said they would reject the application if it became clear the applicants were homosexual.

Almost half of the respondents said they followed a policy of informing potential birth parents before placing a child with lesbian or homosexual individuals. Most did not object.

The study suggested homosexual parents might have a better chance of adopting children with special needs. Almost one third of agencies specializing in special needs children said they specifically reached out to same sex couples.