Colin Powell danced and sang to Olu Maintain's hit Yahoozee
Ex-US Secretary of State Colin Powell has joined a hip-hop band on stage in London to dance and sing in a celebration of African culture.
America's former top diplomat took centre stage along with Nigerian performer Olu Maintain, who sang his hit Yahoozee.
It is not clear if Mr Powell was aware that the song was about Nigeria's notorious internet fraudsters.
The song tells of an easy-money lifestyle of women, cars and alcohol.
The scammers, known as "yahoo yahoo boys" make money by advance fee fraud, known as "419" after the legal statute that outlaws it.
Nduka Obaigbena, publisher of Nigeria's This Day newspaper which sponsored the Africa Rising Festival in London, said it was a misunderstanding.
"Mr Powell could not have been aware of the lyrics of the song," he told the BBC.
The former general had been addressing the crowd at the Royal Albert Hall when the musicians came on stage.
"It would have been rude for him to have refused," he said.
Olu Maintain - real name Olumide Edwards Adegbolu - says his song is a satire, deriding "yahoo-yahoo" culture, not glorifying it.
"The message of the song is that if you want the lifestyle of drink cars and women you have to work hard, hustle means work, not cheat," he told the BBC.
Mr Powell told the audience his own black identity mattered as much as ever and that Africa, with hard work and foreign investment, could prosper like Asia and Eastern Europe.
"I stand before you tonight as an African-American," Mr Powell said.
"Many people have said to me you became secretary of state of the USA, is it still necessary to say that you are an African-American or that you are black, and I say, yes, so that we can remind our children.
"It took a lot of people struggling to bring me to this point in history. I didn't just drop out of the sky, people came from my continent in chains."
A lot of wrongs had been done to Africa by Western powers faced with "an iron curtain and a bamboo curtain", he said in an apparent reference to the USSR and communist China.
These barriers had fallen, he argued.
"Asia is expanding, it created jobs for people, and Eastern Europeans are doing the same... it's now Africa's turn."
Wads of cash
But the theme of the song he was dancing to is quite different.
The Nigerian smash hit, sung in Yoruba and pidgin by Olu Maintain is about people spending money they made from US fraud victims.
The BBC's Andrew Walker in Abuja says the track is also accompanied by a dance move popular in Nigerian clubs that involves hand movements that represent stacking up wads of dollar bills.
"Some people came into the world to work, some people came into the world to live large," the song says.
Colin Powell, a distinguished former military commander, served as US secretary of state during the first term of the Bush administration, from 2001 to 2005.