Barack Obama has waded into a race row surrounding America's most prominent black scholar, accusing police of acting "stupidly" for arresting the man after he forced his way into his own home.

But even as he portrayed the case as a sign of his country's continuing racial divide, America's first black president joked that he would face an even worse fate if he ever tried to jemmy his way into the White House. "Here," he told a press conference, "I'd be shot."

Proessor Henry Louis Gates, director of Harvard’s W.E.B. Du Bois Institute for African and African-American Research, was arrested last Thursday night.

The 58-year-old, a friend of Mr Obama, was seen by a passer-by as he and his driver attempted to prise open the front door of his home in Cambridge, Massachusetts.

The passer-by alerted the police and by the time a uniformed, white officer arrived Mr Gates was inside his home and reporting the faulty front door to the Harvard Real Estate office.

In his first televised interview since the arrest, Mr Gates told CNN last night that he had told the officer: "This is my house. I'm a Harvard professor. I live here."

He then showed him his Harvard University identification card and driver's licence but said that when he asked the officer for his name and his badge, he did not respond.

“He didn’t say anything. I said, ’Why are you not responding to me?’” Mr Gates recalled. “Are you not responding to me because you’re a white police officer and I’m a black man?"

But when the professor then stepped outside at the officer’s request, he was handcuffed – first with his hands behind his back despite being handicapped and requiring the use of a cane – arrested and spent four hours in police custody before being released. A charge of "tumultuous behaviour" was later dropped.

Mr Gates, who was named by Times magazine in 1997 as one of the 25 most influential people in the United States, said that seeing his own police mugshot had been "terrifying".

He is now considering legal action against the Cambridge police. “What it made me realize was how vulnerable all black men are, how vulnerable all people of colour are and all poor people to capricious forces like a rogue policeman," he said.

He has already received apologies from Denise Simmons, the Cambridge mayor, and Deval Patrick, the Massachusetts state governor, both of whom are black.

But the white officer involved, Sergeant James Crowley, has refused to apologise and police insist that Mr Gates was responsible for his own arrest because he overreacted and shouted at the policeman.

The case has been widely discussed on talk shows and in blogs and newspaper forums and was raised last night as Mr Obama gave a prime-time news conference.

The President acknowledged his friendship with Mr Gates and admitted that he did not know the full facts of the incident.

But he added: “I think it’s fair to say: number one, any of us would be pretty angry; number two, that the Cambridge police acted stupidly in arresting somebody when there was already proof that they were in their own home; and number three - what I think we know separate and apart from this incident - is that there is a long history in this country of African-Americans and Latinos being stopped by law enforcement disproportionately, and that’s just a fact.”

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