Tony Blair refused to bow to demands to apologise for Britain's role in the slave trade yesterday, expressing instead "deep sorrow and regret" for the suffering it caused.

Britain's first black archbishop, Dr John Sentamu, had earlier joined calls for the Prime Minister to "go a bit further" than such expressions of regret.

But Mr Blair - in a video message recorded for a major event in Ghana to mark the 200th anniversary of Britain passing a slavery abolition law - stopped short of a full apology.

He said the legislation, pushed through Parliament by William Wilberforce, had begun the process of ending "one of the most shameful enterprises in history."

He said: "So it is right that this anniversary is being marked today here in Ghana's Elmina Castle, the scene of such inhuman abuse, and in cities across the UK, in Liverpool, Hull, Bristol and London, which played their role in this deplorable trade.

"It is an opportunity for the United Kingdom to express our deep sorrow and regret for our nation's role in the slave trade and for the unbearable suffering, individually and collectively, it caused."

He paid tribute to people of all races who had contributed to the worldwide campaign against slavery.

He said: "They prayed, organised, marched and sometimes fought to change our world for good. We must remember them all today and celebrate the sheer power of the human spirit to overcome such injustice.

He said there was still a great deal to do in tackling modern slavery, such as the forced recruitment of child soldiers, human trafficking and bonded labour.