Relatives of some who died on the Titanic are on a voyage to the North Atlantic site where the liner sank, to mark 100 years since the disaster.

MS Balmoral has left Southampton docks, retracing the route of the ill-fated liner's maiden voyage.

The ship, carrying 1,309 passengers - the same number as were on the Titanic - is due to reach the wreck site next weekend for a memorial ceremony.

The Titanic hit an iceberg on 15 April 1912 and sank, killing about 1,500.

The Balmoral left England's south coast shortly after 14:45 GMT and will follow the Titanic's exact route - near Cherbourg in north-west France and then stopping in Cobh on the south coast of County Cork, Ireland - to the spot where the liner sank.

Passengers will gather for a service to be held at 02:20 GMT next Sunday - 15 April - to mark the moment of the sinking.

Analysis The story of the Titanic has been the subject of countless films, books and documentaries. But for many on board this centenary cruise there is a deeply personal connection with what happened in April 1912. They include the relatives of survivors of the tragedy and those who were killed when the ship sank after striking an iceberg. They are joined by enthusiasts - so-called 'Titanoraks'. Among them are a couple who are using the trip as their honeymoon after a themed wedding in Belfast where the ship was built. They are tracing the route taken by the Titanic and stopping to pay tribute at the spot in the Atlantic Ocean where the wreck still lies deep below. Many have no doubt that, for them, this will be an incredibly emotional journey.

Some relatives were bringing wreaths of flowers and family artefacts in memory of those who died.

Passengers making the journey, who come from more than 20 countries, include relatives of survivors, authors, historians and people who are fascinated by the Titanic story.

They will eat meals from the Titanic's original menu and attend lectures given by historians and experts.

Philip Littlejohn, grandson of survivor Alexander James Littlejohn and the only Titanic relative to have made the dive to the wreck site, said: "I'm sure my grandfather, a 1st Class Steward on RMS Titanic, would be proud to know his story will be shared with the passengers on this historic cruise.

"It will be an emotional moment when we are over the wreck site, where I dived in 2001, and where my grandfather left Titanic rowing Lifeboat 13."

Jane Allen, whose great uncle Tom Pears died in the disaster, is among passengers who have paid up to £6,000 ($9,000) to join the commemorative voyage.

"I don't think it's ghoulish or macabre at all," said Mrs Allen, from Devon.

"I've been to the World War II and I cemeteries in various places across the world. I think it's always important to remember."

Peter Hill, 61, from the Isle of Man, echoed those sentiments, saying: "I think the cruise has been tastefully done. It's not a cheap cruise by any means."

The retired policeman who is making the journey with his wife, Lynda, also 61, said he had a personal link to the ship.

'Family history'

"My grandfather was a Lloyd's underwriter of the ship and lost a lot of money when she sank. He was a very wealthy man and had to sell one of two farms to pay for the losses," he said.

"I'm a big fan of the story and I have 38 books about it and it's always been part of my family history."

Carmel Bradburn, 55, a Briton now based in Adelaide, Australia, bought her partner Andreas Storic, 51, on the memorial cruise.

She said: "I'm fanatical about the Titanic. It's an amazing story and I have been reading about it but I'm not so keen on the film. Just think we are doing this 100 years later."

Image caption Some people dressed in period costume for the trip

And her partner disagreed with the notion that the journey was "morbid".

"Remembering those who died is not morbid," he said.

From the wreck site, the Balmoral will go on to Nova Scotia, where some of the bodies of those who died are buried, and then onto New York City, the destination the Titanic never reached.

The Balmoral was chartered for the 12-night journey by Miles Morgan Travel.

Miles Morgan, managing director, said the company had sought to make the voyage "a sympathetic memorial to the passengers and crew who lost their lives".

The Titanic hit an iceberg at 23:40 (ship's time) on 14 April 1912, some 460 miles (740km) from Newfoundland and took two-and-a-half hours to sink.

About 1,300 passengers and 900 crew members were on board the liner when it sank. They ranged from millionaires to poor emigrants.

About 713 people were rescued by RMS Carpathia.

In 1985, Dr Robert Ballard discovered the wreck 2.5 miles (4km) below the surface of the north Atlantic.