The traditional African rulers, who are seeking inclusion in the forthcoming constitutional amendment in Nigeria, should first apologize for the role they played in the slave trade, a Nigerian rights group has demanded.

"We cannot continue to blame the white men, as Africans particularly the traditional rulers, are not blameless," said the Civil Rights Congress in a letter to chiefs. The letter said some collaborated or actively sold off their subjects. The group said it was time for African leaders to copy the US and the UK who have already said they were sorry.

It urged Nigeria's traditional rulers to apologize on behalf of their forefathers and "put a final seal to the history of slave trade".

Civil Rights Congress President Shehu Sani said "We felt that for them to have the moral standing to be part of our constitutional arrangement there are some historical issues for them to address. One part of which is the involvement of their institutions in the slave trade."

He said that on behalf of the buyers of slaves, the ancestors of these traditional rulers "raided communities and kidnapped people, shipping them away across the Sahara or across the Atlantic". Millions of Africans were forcibly transported to the Americas over a period of about 450 years from the middle of the 15th Century.

More than a million people are thought to have died while in transit across the so-called "middle passage" of the Atlantic, due to the inhuman conditions aboard the slave ships and brutal suppression of any resistance. Many slaves captured from the African interior died on the long journey to the coast.