"We know what it might take. What we haven't seen is a consistent, steady application of some of these models over time in Africa, and I think that now is the time to start," he said in an interview with AllAfrica.com.

"I think that it's very important for African leadership to take responsibility and be held accountable," said Obama, the first black U.S. president. His father was born in Kenya.

Obama said he thought part of what had hampered advancement in Africa was that excuses had been made for many years for corruption and poor leadership.

"You're not going to get investment without good governance," he said. "If government officials are asking for 10, 15, 25 percent off the top, businesses don't want to invest there."

Obama held up Ghana as a model, saying he hoped his visit would highlight the country's effective government. Obama arrives in Ghana on Friday, following the G8 Summit in Italy and an official visit to Moscow he just concluded.

He said Ghana had had a series of successful elections in which power was transferred peacefully and the new Ghanaian president, John Atta Mills, had shown a commitment to democratic principles that ensure stability in a country.

"Countries that are governed well, that are stable, where the leadership recognizes that they are accountable to the people and that institutions are stronger than any one person have a track record of producing results for the people," Obama said.