Donald Trump 'questions Obama's birthplace'

Donald Trump has publicly expressed doubt as to whether US President Barack Obama was born in the United States.

The possible Republican presidential candidate told Fox News host Bill O'Reilly that he believes Obama should release his birth certificate in order to prove that he is eligible to hold the country's highest office.

After O'Reilly cited that two Honolulu newspapers carried birth announcements the week the US president was born, Trump charged that such documents could have been fraudulently created.

"I grew up with Wall Street geniuses," the Celebrity Apprentice star said. "What they do in terms of fraud and how they change documents [is very common]."

Trump went on to assert that Obama's birth is a legitimate political issue because it affects the very nature of who can be elected to the presidency.

"If you are going to be the president of the United States, you have to be born in this country. There is a doubt as to whether or not he was born [here]," he explained.

"People are afraid to talk about the subject. They are afraid to confront [O'Reilly] or anybody about this subject… People have birth certificates. [Obama] doesn't have a birth certificate. Now, he may have one, but there's something on [it], maybe religion [or] maybe it says he's a Muslim. I don't know."

The mogul then added: "If he wasn't born in this country, it's one of the great scams of all time."

Trump has promised that he will make his final decision about a bid for the White House prior to June.

The Celebrity Apprentice airs Sundays on NBC.

> Donald Trump, US Rep spar over political bid

Watch Donald Trump's exchange with Bill O'Reilly below: