On Monday, Tony Blair will issue, if not a full formal apology, at least a statement of "deep sorrow" for Britain's role in the trans-Atlantic slave trade, a business that, between the 16th and 19th centuries, forcibly transported an estimated three million black Africans across the Atlantic and into servitude in the New World. The statement will appear in the New Nation, a British Afro-Caribbean community magazine.

Blair's comments come in advance of the 200th anniversary of the Abolition of the Slave Trade Act, the much fought-over piece of legislation that, in 1807, finally made it illegal for British subjects to capture and transport slaves (although not to physically own them).

"It is hard to believe that what would now be a crime against humanity was legal at the time," Blair says in his statement.

"I believe the bicentenary offers us a chance not just to say how profoundly shameful the slave trade was, how we condemn its existence utterly and praise those who fought for its abolition, but also to express our deep sorrow that it could ever have happened and rejoice at the better times we live in today."

Britain was certainly not the only country to be involved in, and to benefit from the pernicious trans-Atlantic trade in human lives, nor was it by any means the first (the word "slave", incidentally, comes from the Byzantine Greek "sklabos.")

From the 15th to the 17th centuries, Portugal had a near-monopoly on the export of slaves from Africa, and by the time it eventually abolished slavery -- in 1869, one of the last European countries to do so -- had been responsible for the transportation of an estimated 4.5 million people into servitude in the colonies of the New World, some 40 percent of an estimated total of 10-12 million (some put the overall figure as high as 17 million.)

Spain, the Netherlands, France, Denmark and North America were all significant players in the trans-Atlantic slavery machine, as were the native rulers of the 170-odd city-states and kingdoms of West Africa from which the slaves were actually abducted.

On the other side of the continent, meanwhile, Arab traders were responsible for the enslavement of some 14-20 million Africans (figures in this case are even harder to estimate since the East African Arab slave trade started much earlier than the West African European one, going right the way back to the 8th Century AD).

If Britain is not unique in its guilt and responsibility, however, it was certainly the worst transgressor during the 18th century, when slave trading was at its peak and British ships and merchants accounted for some 2.5 million of the estimated 6 million Africans carried in chains across the Atlantic.

"The transatlantic slave trade stands as one of the most inhuman enterprises in history," says Blair in his article.

"It is only right that we recognize the active role that Britain played in this trade. British industry and ports were intimately intertwined with it. Britain's rise to global pre-eminence was partially dependent on a system of colonial slave labor and, as we recall its abolition, we should also recall our place in its practice."

While Britain led the way in bringing to an end the trans-Atlantic slave trade from which it had so profited, its government has to date refused to offer any sort of official and unequivocal word of apology for that trade, although in 1999 Liverpool City Council did pass a formal motion of apology for the city's involvement in slaving (the Church of England did likewise in February 2006).

Britain is certainly not alone in its refusal to say sorry. Of the other major slaving nations only France has really grasped the slavery nettle, passing the so-called Taubira Law in 2001 -- named after its proposer, politician Christiane Taubira -- which declared the trans-Atlantic slave-trade a crime against humanity.

In 2001 Britain was actually one of four nations -- along with Spain, the Netherlands and Portugal -- who opposed the issuing of a blanket EU apology for slavery.

Outright apologies of this sort can raise complicated legal issues of redress and compensation, which is why they are so rare in politics (the Australian government, for instance, has steadfastly refused to apologize for its past treatment of native aborigines).

Although in his Monday article Tony Blair stops short of issuing the full and unequivocal mea culpa for which some campaigners were pushing, his words have been generally welcomed as a bold act and a step in the right direction (especially since they were allied to UK sponsorship of a special UN resolution calling on members to hold special commemorative events to mark the bicentenary of the 1807 abolition).

"It's pretty much as close to an apology as he can give taking into account the advice he has been getting from the Foreign Office in terms of the threat of legal action," Michael Eboda, editor of The New Nation, was quoted as saying in The Times newspaper. "I am pleased with it."

Whether any of the many other countries involved in the trans-Atlantic slave-trade will follow Britain's lead, as they did two centuries ago in abolishing that trade, remains to be seen.