For 85 years, the sinking of the SS Mendi has been a shameful scar on British history.

More than 600 South African war volunteers, who had left their homes and families to answer Lord Kitchener's call, died when their ship was rammed by a British liner in the English Channel.

Around 100 relatives, joined by South African government officials and royal family members from the Eastern Cape, visited Sussex at the weekend to pay tribute to the victims of one of the First World War's forgotten catastrophes.

A memorial stone was unveiled at Newtimber Church after a service of reconciliation.

The service marked the start of a long-awaited resolution to the resentment felt by communities in rural South Africa at the way their men were taken from them with no recognition or apology.

The delegation was led by Chief Malizole Ndamase, 65, whose grandfather, Chief Bokleni Ndamase, rallied the finest warriors from the Pondo kingdom of the Eastern Cape to support Britain's war effort on the Western Front.

He said: "There's been a lot of bitterness.

"But we've come here to Britain to forget about the past and turn this tragedy into a blessing."

The tribesmen boarded the SS Mendi at Cape Town on January 16, 1917, bound for Le Havre via Plymouth.

They had been on board for almost five weeks when disaster struck at about 5am on February 21, 12 miles off St Catherine's Point on the Isle of Wight.

In thick fog a British liner, the SS Darro, crashed into the Mendi.

As the Mendi went down, sinking within 20 minutes and killing all 650 troops and officers on board, the liner sailed away without stopping to help.

Members of City Gate Church in Brighton learned of the little-known tragedy while visiting South Africa two years ago.

For the return trip, many opened their homes to the ancestors of those who died.

Church leader Andy Au apologised on behalf of Britain.

But there is still anger that the authorities tried to cover up the truth for so long.

Many of the victims' relatives have still not received official notification and there has been no official apology from the British government.

A South African choir sang alongside Citygate worshippers at Saturday's service and many members of the Brighton church wore South African native dress.

South African church leader Dr Joseph Kobo likened the ceremony to taking the victims' bones back to their families.

He said: "We're not here to dig the wounds of the past. We want to use history as a teacher, for a brighter tomorrow."

But it was clear the deep hurt will not be easily erased.

South African foreign minister Dlamini Zuma said: "It's strange to have waited almost a century to acknowledge those brave men who made the supreme sacrifice for the British Empire."

She paid tribute to the ordinary people of Britain who had brought the communities together in a way the governments had not.

An identical memorial stone will be laid in South Africa in September.

Mr Au said his church would continue to work closely with its counterparts in South Africa.

He said: "The story of the SS Mendi is great and sad at the same time.

"It's a story full of bravery but also of hurt.

"Hearing it, we felt guilty being British citizens. I felt we had to do something."

Newtimber Hill was chosen for the memorial because it overlooks the Channel and resembles the hilly regions the tribesmen came from.

The Earl of Buxton, then Governor General of South Africa, is buried at Newtimber Church.

His daughter, Lady Alathea Elliot, attended the service and was thanked for helping finance some of the visitors' journeys.