Brazil has become the latest country to pave the way for same-sex marriage after it approved a measure changing the legal definition of a "civil union" to simply be between two people, without making it exclusive to a man and a woman.

The measure passed the Brazilian senate, its first legislative step in congress, after the issue had been disputed for 16 years, the Associated Press reported.

The Senate still does not approve of gay marriage, but Brazil's judiciary has already moved toward legalising same-sex marriages after state courts last year began allowing civil unions between homosexuals to be converted to full marriages.

The bill still needs to pass other Senate committees before going to a full vote, but Sen. Marta Suplicy, who sponsored the mandate, has argued that it is time for law makers to put into the penal code what state courts are already allowing.

Homosexuality in Brazil remains a controversial issue. Brazilian Christians are largely against civil unions, a 2010 poll found, with only 35 per cent of respondents to the study declaring themselves in favor of creating homosexual civil unions.

The issue was more divisive among the non-religious population, but even then a 56 per cent majority declared themselves against same-sex civil unions.

Earlier this month, a Brazilian apologist fired back against a BBC report that he says grossly overestimated the number of people attending "all-inclusive", or gay-friendly churches around the country.

The initial report had argued that 10 "all-inclusive" congregations had a combined total of about 10,000 members, but according to Johnny Bernardo, founder of the Institute for Religious Research (INPR), the number of congregation members in liberal churches was less than half that; only 4,500 members in total.

Even these liberal churches, however, face a strong resistance from mainstream evangelical and Catholic churches in Brazil who adhere to the traditional definition of marriage as between one man and one woman.

Argentina is the only other South American country that currently has fully legalised same-sex marriage, as do nine other nations worldwide. In the US, only the states of Massachusetts, Connecticut, Iowa, Vermont, New Hampshire, New York and DC have such provisions.