The violin played by the bandmaster of the Titanic as the ocean liner sank has been unearthed - in an attic.

Survivors of the Titanic have said they remember the band, led by Wallace Hartley, playing on deck even as passengers boarded lifeboats after the ship hit an iceberg.

Hartley's violin was believed lost in the 1912 disaster, but British auctioneers Henry Aldridge & Son said an instrument unearthed in 2006 has undergone rigorous testing and proven to be Hartley's.

"It's been a long haul," said auctioneer Andrew Aldridge, explaining the find had initially seemed "too good to be true."

The auction house spent the past seven years and thousands of pounds determining the water-stained violin's origins, consulting numerous experts including government forensic scientists and Oxford University.

According to the BBC, it is thought to be the most important artefact discovered since the sinking.

The auction house said the rose wood instrument has two long cracks on its body, but is "incredibly well-preserved" despite its age and exposure to the sea. It estimated the violin is worth six figures.

Hartley was one of the 1,517 people who perished when the Titanic struck an iceberg 565 kilometres south of Newfoundland on April 15, 1912.

Some reports at the time suggested Hartley's corpse was found fully dressed with his instrument strapped to his body, though there was also speculation the violin floated off and was lost at sea.

Henry Aldridge and Son said it researched the violin's story with a Hartley biographer as the instrument underwent forensic testing, uncovering documents that showed Hartley was found with a large leather valise strapped to him and the violin inside.

The violin was oiginally returned to Hartley's fiancé Maria Robinson before being given to Bridlington Salvation Army band, East Yorks, when she died in 1939.

Band leader Major Renwick passed it to one of his musicians but it was stashed away in an attic. 

Testing by the UK Forensic Science Service showed corrosion deposits were considered "compatible with immersion in sea water," while a silver expert studied a plate on the violin's neck to determine if it fit the time profile.

Henry Aldridge & Son said the violin will go on public display at the end of the month at Belfast City Hall, less than a mile from where Titanic was built.

- AP