The U.S. House of Representatives has approved a proposal to repeal the "don't ask, don't tell" policy that lets gays serve in the military only if they don't disclose their sexual orientation.

Thursday's 234-194 vote to overturn the military's policy delivered a victory to President Barack Obama and gay rights groups. It also reflected a view among many in Congress that the United States is ready for a military in which gays and straights can stand side by side in the trenches.

"I know that our military draws its strength on the integrity of our unified force, and current law challenges this integrity by creating two realities within the ranks," said Representative Susan Davis, a Democrat.

Republicans, who voted overwhelmingly against it, cited statements by some military leaders that they need more time to study how a change in the law could affect the lives and readiness of service members.

The House vote came just hours after the Senate armed services committee took the same course and voted 16-12 in favour of repealing the 1993 law. In both cases, the measure was offered as an amendment to a defence spending bill.

Obama and leading Democrats, including House Speaker Nancy Pelosi, actively support the repeal so that gays can serve in the military without fear of being exposed and discharged.

In a statement after the House vote, Obama hailed the day's congressional action as "important bipartisan steps toward repeal."

"This legislation will help make our armed forces even stronger and more inclusive by allowing gay and lesbian soldiers to serve honestly and with integrity," Obama said.

"This is the beginning of the end of a shameful ban on open service by lesbian and gay troops that has weakened our national security," Joe Solmonese, president of Human Rights Campaign, a leading gay rights organization, said after the Senate panel's vote.

During an all-day House debate on the bill approving more than $700 billion in spending for defence programs, Republicans repeated statements by military service chiefs that Congress should not act before the Pentagon completes a study on the impact of a repeal.

Congress going first "is the equivalent to turning to our men and women in uniform and their families and saying, 'Your opinion, your view, do not count,"' said Representative Howard (Buck) McKeon, the top Republican on the House armed services committee.

Democratic supporters stressed that the amendment was written so that the repeal would not go into effect until after the Pentagon publishes in December the results of a survey on how service members and their families view the change, and until the president, the defence secretary and the Joint Chiefs of Staff certify that the repeal will not affect the military's ability to fight.

The chief sponsor of the amendment, Democratic Representative Patrick Murphy, who served in the Iraq War, said that when he was in Baghdad "my teams did not care whether a fellow soldier was straight or gay if they could fire their assault rifle or run a convoy down ambush alley and do their job so everyone would come home safely."

House Majority Leader Steny Hoyer said that of the 13,500 members of the military who have been discharged under "don't ask, don't tell," more than 1,000 filled critical occupations, such as engineers and interpreters.

He compared the arguments of the opposition to 1948 speeches in Congress when lawmakers warned that integrating the troops would undermine morale in the military.

The drive to repeal the ban still faces a tough road ahead in the full Senate, where Republicans are likely to filibuster it.

"I think it's really going to be very harmful to the morale and effectiveness of our military," said Senator John McCain, the top Republican on the armed services committee and a leading opponent of the repeal.

The Senate probably will take up the bill next month.

Defence Secretary Robert Gates has said he supports repeal but would prefer that Congress wait for the December report.

Under "don't ask, don't tell," military leaders don't investigate a service member's sexual orientation as long as the person does not disclose that he or she is gay or has a same-sex relationship, which are grounds for dismissal.