The relatives of victims of Russia's Kursk submarine disaster are appealing to the European Court of Human Rights for an investigation into the tragedy.
Many in Russia believe some sailors could have been saved
Boris Kuznetsov, a lawyer for families of 50 sailors, said they were contesting Russian court rulings that have stopped the case being reopened.
He says there is evidence that some sailors were alive more than eight hours after a blast crippled the sub.
All 118 sailors died when the Kursk sank in the Barents Sea in August 2000.
Experts describe the sinking as the worst naval disaster in Russia's peacetime history.
Military prosecutors closed investigations into the disaster in July 2002, concluding that no sailors could have survived long enough after the explosion to be rescued.
But many believe that 23 sailors who survived the initial blast might have been saved, had the Russian navy reacted in time.
A note found on the body of one sailor, Dmitry Kolesnikov, revealed that the group was trapped alive in one section of the submarine. They died hours later of suffocation.
Mr Kuznetsov, who is about to publish a book on the tragedy, said the arguments had not been properly addressed.
He said he had launched the appeal because of the failure of the Russian authorities to reopen the case, notably in a Moscow court decision taken last year.
"The main reason is the limited access to justice and the lack of well-grounded rulings in reply to arguments of the defence stating that the sailors were alive ... for over two days," he told Russian radio.
The relatives have said they do not want financial compensation but are merely seeking the truth.