Last week saw the publication of various theories that the ship sank because ice-spotting binoculars were locked away, that rivets were of inferior quality, that a report of ice ahead never made it to the bridge and that there was an out of control fire in the engine room.

But Una Reilly, chair and co-founder of the Belfast Titanic Society, is annoyed at what she sees as an attempt to exploit a very solemn week. "All these theories have been out before and it really seems as though they have all come to the fore during the anniversary week in order to publicise books and so on," she said.

"There are other theories too, for example that the rudder was faulty, but the truth is that the Titanic sank because she hit an iceberg."

She said relatives of the dead had met at the memorial in the Belfast City Hall grounds on Tuesday for "a quiet and dignified event".

"We need to remember that for many people this is still a very personal matter," she added.

One author, Ray Boston, devoted 20 years to researching the vessel and raised the theory this week that a raging fire in the ship was partly responsible for the disaster.

Mr Boston quotes Bruce Ismay, the managing director of the White Star Line, which owned Titanic, where Mr Bruce told investigators he was forced by John Pierpont Morgan, the ultimate owner of the ship, to instruct the crew to cross the Atlantic at full speed.

Gamble

"Morgan thought it was necessary, in order to justify his gamble, that they should reach New York and unload all the passengers before the inevitable explosions occurred," Mr Boston claims.

He believes that fireman J Dilley, a stoker aboard Titanic who survived, added weight to the suggestion of an uncontrollable fire.

"We didn't get that fire out and among the stokers there was talk that we'd have to empty the big coal bunkers after we'd put the passengers off in New York and then call on the fireboats there to help us put out the fire," said Mr Dilley.

An inquiry into the disaster, presented to Parliament in the summer of 1912, found the ship's speed was "excessive" considering it was off the coast of Newfoundland, and that additional look-outs should have been posted. When the lone look-out spotted the approaching iceberg, it was already too late to avoid disaster.

Mr Boston suggests Mr Morgan quietly cancelled his ticket for the maiden voyage the day before the ship set sail because he knew about the fire on board.

But Ms Reilly said it was utter nonsense: "Such fires were quite common in ships back then because coal dust ignited with the heat," she said. "But according to the inquiry in 1912, stoker Fred Barrett said this fire on the Titanic had definitely been put out."