Russia's Defence Minister Sergei Ivanov has said that the loss of a nuclear-powered submarine with 10 crew in the Barents Sea was largely caused by negligence of navy officials.
The incident happened as the 40-year-old vessel - a November class K-159 - was being towed to a scrapyard in a heavy storm early on Saturday morning.
K-159 NUCLEAR SUB
November class sub
Up to 86 crew
Can carry two nuclear reactors
Can be armed with low-yield nuclear torpedoes
Subs of this class entered service in late 1950s
Sources: Jane's Fighting Ships, Danish experts
Mr Ivanov - who on Sunday went aboard a missile cruiser to inspect the site of the incident - said the submarine's conning-tower hatch was open when it sank.
The commander of the region's submarine force has been suspended and a number of navy officials have been charged with violation of navigation rules, according to Interfax news agency.
A Russian military prosecutor opened an inquiry into the incident on Saturday, after Russian President Vladimir Putin pledged "a thorough investigation" into the matter.
On Sunday, the Russian Navy's northern fleet is holding a day of mourning for the K-159 crew. So far, only one sailor has been rescued, and two bodies have been recovered.
Mr Ivanov said on Saturday that it was impossible that any of the seven missing sailors who likely went down with the submarine would be found alive.
The vessel was powered by two nuclear reactors which were shut down 14 years ago and Russian officials said there were no weapons on board.
Russia has been monitoring radiation levels in the area and Mr Ivanov was quoted by Interfax as saying that no changes have been registered.
Disaster waiting to happen
"Here again this Russian habit of relying on mere chance and hoping that everything will work just this time showed itself," Mr Ivanov was quoted by Interfax as telling reporters on board the Marshal Ustinov missile cruiser.
"This confirms yet again the simple truth that all instructions and orders must be taken seriously. Otherwise, sooner or later tragedies involving the death of innocent people will occur," he added.
The submarine sank about 5 kilometres (3 miles) off Kildin Island after one of four floating hulls was ripped off in a fierce storm.
Initially, Russian navy experts said it was on the sea bed 170 metres deep (557 feet). But on Sunday they said the depth was 238m (780 feet).
They said the vessel was lying horizontally with a three-degree list to starboard.
The Russian Navy has said it will attempt to raise the submarine.
But some Russian military experts have expressed doubts about the feasibility of salvaging the submarine, saying Russia does not have the necessary resources to accomplish the operation.
The latest incident comes three years after Russia's worst peacetime naval disaster, when all 118 crew of the nuclear submarine Kursk died when it sank in the Barents Sea on 12 August 2000.
When the Kursk sank, Russia's Government and military were slow to admit what had happened, and slow to ask for foreign help in the search for survivors.
This caused an avalanche of protests both in Russia and abroad, seriously denting the popularity of President Putin and the government.
The BBC's Damian Grammaticas says that this time at least the government has released information promptly.
Since the collapse of the Soviet Union in 1991, Russia has decommissioned about 190 nuclear powered submarines.
But experts say more than half of them still have nuclear fuel in their reactors.
NUCLEAR POLLUTION IN THE BARENTS AND KARA SEAS
1. Techeniya Fjord: 2 reactors without spent fuel dumped in 35-40 metres of water in 1988
2. Tsivolko Fjord: 3 reactors without spent fuel from the nuclear powered icebreaker Lenin. 60% of the fuel elements from the reactors packed in a container and dumped at the same location
3. Kara Sea: 6 reactors containing Uranium, together with 10 empty reactors and 11,000 radioactive waste containers
4. Stepovogo Fjord: K-27 submarine fitted with two experimental liquid metal cooled reactors dumped at depth of 50m in 1981
5. Abrosimov Fjord: 3 reactors with spent fuel, 3 without dumped in 20m of water in 1965 and 1966
Zapanaya Litsa: 21,860 spent fuel assemblies, Vidyaevo: spent nuclear fuel in 17 laid-up submarines, Severomorsk: spent nuclear fuel in 2 laid-up battle cruisers, Gremikha: 767 spent fuel assemblies; 6 liquid metal cooled reactor cores, spent nuclear fuel in 19 laid-up submarines, Severodvinsk: Approx. 588 spent fuel assemblies stored
Source: Bellona Foundation