The White House released President Barack Obama's Hawaii long-form birth certificate Wednesday in an attempt to silence the so-called "birthers" who say he is foreign-born.

"Yes, I was born in Hawaii," Obama said at a White House briefing that was carried live by most U.S. TV networks. He confirmed that he was, in fact, born in the United States and is therefore constitutionally able to hold the highest office in that country.

The U.S. constitution requires that presidents be "natural-born" Americans.

For years, Obama has been dogged by unfounded rumours — fanned by such potential Republican presidential candidates as Donald Trump — that he may have been born in Kenya.

"Over the last two and a half years, I have watched with bemusement; I have been puzzled at the degree to which this thing just kept on going," Obama told reporters as he outlined the many documents the White House had previously released that prove his Hawaiian birth.

"We do not have time for this kind of silliness," Obama said, noting the serious problems facing the U.S.

"We're not going to be able to solve our problems if we get distracted by sideshows and carnival barkers."

In New Hampshire, Trump said he was "proud" to have played a role in getting Obama to release the document. But he was not quite ready to give the president the benefit of the doubt.

U.S. President Barack Obama tells White House reporters Wednesday that he released a copy of his original birth certificate because the country doesn't have time for the 'distraction' and 'silliness' of questions about where he was born. (J. Scott Applewhite/Associated Press)

"We have to look at [the document]. We have to see, is it real, is it proper?" he asked. "What's on it? I hope it checks out beautifully."

Rumours of Obama's foreign birth have persisted despite the release by the Obama campaign three years ago of his standard short-form birth certificate. This week, Obama requested his original birth certificate from Hawaiian officials.

Obama's personal lawyer flew to Hawaii to retrieve two certified copies of the document and brought them back to Washington.

Polls have suggested that a significant minority of Americans — especially Republican party supporters — doubt that Obama was born in the U.S.