The Archbishop of York, Dr John Sentamu, has said that Prime Minister Tony Blair should "go a bit further" and make a formal apology for the slave trade on behalf of Britain.

The call came ahead of a ceremony in Ghana to mark the 200th anniversary of the abolition of the slave trade on Sunday, in which the UK's first black cabinet minister Baroness Amos, leader of the House of Lords and a descendent of slaves, will say that slavery was "one of the most shameful and uncomfortable chapters in British history".

Mr Blair, who will address the ceremony in Ghana via video link, expressed earlier in the month "deep sorrow" for the slave trade, saying, "We are sorry."

Dr Sentamu said in an interview with the BBC, however, that Mr Blair needs to go further and make a full apology.

"A nation of this quality should have the sense of saying we are very sorry and we have to put the record straight," he said.

Dr Sentamu joined the Archbishop of Canterbury and other church leaders as they walked through London on Saturday in reflection and repentance for the complicity of the church in the slave trade.

The Archbishop of Canterbury challenged Christians to open their eyes and "see" where people might still be in slavery today, calling on Christians to be "agents of release" and "people committed to freedom".

"By God's grace and the work of some extraordinary human beings 200 years ago, people began to see. It took a long time - an embarrassingly long time," said Dr Williams.

He pointed to the horror of modern slavery like sex trafficking.
"For a long time it's been possible for many people not to open their eyes to those things," he said.

Churches across the UK are holding special services and events throughout Sunday to mark the anniversary of the abolition of the slave trade.

Christians and politicians remain divided over the need for an apology. The head of the African and Caribbean Evangelical Alliance, the Rev Katei Kirby, said an "act of repentance" was needed more than a statement of repentance. Pastor Agu Irukwu, head of leading London Pentecostal church Jesus House, said that an apology would be "hollow" unless African, Caribbean and Caucasian communities were to "come out of their comfort zones and engage with each other".

Tory leader David Cameron said, meanwhile, "I don't actually think that one generation can meaningfully apologise for something that a previous generation did."

Instead, he said that "true reparation" was "to make sure that Africa has a chance for peace, prosperity, stability and all the advantages we have in the West".