WASHINGTON (AFP) - President Barack Obama signalled on Monday he will make a strong push for homosexual rights in his second term, vowing in his inaugural speech to fight for equal rights for "our gay brothers and sisters."

Mr Obama became the first president ever to make mention in an inaugural speech of gay rights, earning cheers from activists - and indicating he plans to be more outspoken on the issue than he was during his first four years in office.

"Our journey is not complete until our gay brothers and sisters are treated like anyone else under the law, for if we are truly created equal, then surely the love we commit to one another must be equal as well," Mr Obama said.

He drew a parallel between several watershed rights struggles in United States (US) history - that of women at the landmark Seneca Falls convention in 1848, the civil rights battle in Selma, Alabama, and finally the Stonewall riots in June 1969, widely seen as sparking the gay rights movement.

Gay rights leaders hailed the speech.

Mr Chad Griffin, the president of the Human Rights Campaign, said "The President's unequivocal support for equality is a clarion call that all Americans should receive with celebration."

By mentioning gay rights in his speech, "Obama sent a clear message to LGBT young people...that this country's leaders will fight for them until equality is the law of the land," Mr Griffin said in a statement.

"President Obama is the most pro-LGBT president in American history," said Ms Rea Carey, executive director of the National Gay and Lesbian Task Force.

"These next four years hold great promise for continuing progress in ensuring that LGBT people are fully recognised and valued as part of this country's strength, spirit and solution," Ms Carey said.

"President Obama has repeatedly shown he is willing to fight for us." But before Monday, The President was not always so outspoken in his embrace of gay rights.

A much more hesitant Mr Obama said during his first term that he was "evolving" on the issue of gay marriage.

He often said he was struggling with the issue of extending marriage rights to gays, sometimes voicing his preference for "civil unions" that provided homosexual couples many of the protections and the legal rights that married couples enjoy.

"My feelings about this are constantly evolving. I struggle with this," he said in a December 2010 television, acknowledging he knew that for gays, "it is not enough." But Mr Obama has since made a sharp about-face, becoming an outspoken defender not only of gay marriage but of fuller rights for homosexuals in general.

As the US Supreme Court prepares later this year to take up the issue of gay marriage, his administration has come down squarely on the side of homosexuals seeking the right to marry and against the Defence of Marriage Act federal law.

Same-sex marriage is currently legal in nine states and the US capital, yet barred by federal law. The Supreme Court will hear arguments in March on the sensitive issue, one of the thorniest social disputes in modern America.

Mr Obama now is seeking repeal of the "Defence of Marriage Act" (Doma) which defines marriage as the legal union of one man and one woman and denies federal benefits to married same-sex couples.

During his first term, Mr Obama abandoned his support for the "Don't Ask, Don't Tell" policy put in place during the administration of president Bill Clinton.

That policy discouraged gays who served in the military from revealing their sexual orientation at the risk of being ejected from the service.

Another nod to the homosexual community during Obama's second inauguration on Monday was the selection of gay poet Richard Blanco to read a poem composed for the occasion.

But there have been missteps in his administration's outreach to gays.

It had to fend off criticism from some on the left over negative remarks made by secretary of defense nominee Chuck Hagel in 1998 about a gay diplomat.

And many in the gay community criticized the choice of an evangelical minister known for his fiery anti-gay rhetoric to deliver the benediction at Obama's inauguration ceremony.

Reverend Louie Giglio, 54, head pastor of the Passion City Church in Atlanta, ultimately was forced earlier this month to pull out of the event, over comments he made during the 1990s.

The President's inaugural committee later chose the Reverend Luis Leon, a Cuban emigre with a more gay-friendly theology, to deliver the benediction.