The first operation to enter the shipwrecked Titanic is being launched, in what divers say is a race against time before the rapidly-deteriorating wreck is lost to the sea forever.

The company that owns the salvage rights plans to enter the sunken vessel, which lies off the coast of Newfoundland, in order to recover passengers' jewellery.

It includes a shipment of diamonds worth an estimated $300m carried by two Swiss brothers on the ship's ill-fated journey to New York in 1912.

The wreck was discovered 15 years ago

However, the youngest living survivor of the tragedy, Millvena Dean - who was only nine weeks old when the ship went down - told the BBC that the salvage project was offensive and the ship should be left in peace.

Salvagers believe the ship's officers hastily packed the valuables into leather pouches in the final desperate minutes before the liner sank after hitting an iceberg.

It is thought they were stored in the cargo hold to prevent them being looted.

Not for sale

"We can see through scientific testing that the ship is deteriorating at a very, very rapid rate. The ocean is basically eating the Titanic alive," G Michael Harris, founder of US salvage company RMS Titanic Inc, told the BBC on Saturday.

He said the company hoped to recover some of the first-class luggage from the cargo hold as well as the registered mail.

The wreck is fast deteriorating

Divers also hope to recover the captain's log, which recorded the ship's movements up until the end.

But Ms Dean said it was wrong to allow divers onto the ship, which took the lives of 1,500 crew and passengers.

"Any bits and pieces that have come out from the ship on the seabed - that is alright," she said.

But Mr Harris said it was their job to preserve history. His company has promised not to sell the artefacts but to preserve them for future generations.

The expedition, which is estimated to cost about $5m, has left Norfolk, Virginia,

It is scheduled to reach the Titanic wreckage field in the north Atlantic in about a week.

RMS Titanic's 243-foot Ocean Intervention, which will be joined by two ships from Russia and Britain, each carrying a small submarine, will continue searching until August.