Sub disaster - Steve Rosenberg answers your questions

Russia's Kursk K-141 nuclear submarine went down in the Barents Sea after apparently suffering a catastrophic explosion during naval exercises on 12 August.

All survivors on board have now been confirmed dead.

What do we know about really happened to the Kursk and its crew? Why did the rescue efforts meet with so little success, and why did it seem to take so long for the Russians to ask for foreign help?

BBC correspondent Steve Rosenberg has been covering the disaster and the rescue attempts. He answered a selection of your questions on the submarine tragedy live from Murmansk.

 Click here to watch video coverage of the forum  

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Highlights

Edward D. Kessy, Tanzania: Why did the Russian President take so long to ask for aid or any help from USA and UK?

Steve Rosenberg: I think President Putin would tell you that he didn't wait, he asked for foreign help well in time. But the feeling is in Russia that he waited too long. Why did he wait? Well perhaps he wasn't told the full truth about how serious it was. Questions are being asked about if he was given the right information in time.

Ludmila, Russia: Did Russian's military officials possibly want all the survivors to die? This may have been done to cover the mistakes that could cost the officials their jobs. The other obvious thing is that they wanted to keep everything secret, like they always did in the soviet days?

Steve Rosenberg: Well there are some people in Russia who do believe that. We have heard it on the television and in the newspapers that some people in the Russian Navy have tried to cover this up. And certainly as the week has gone on we have got the feeling that this rescue operation is getting nowhere. But I have to say that if you speak to the Commander of the Russian fleet or the officials they will tell you that everything that could have been done has been. I think it is clear that some people have done their up most to save these people.

Jose Pedro Nascimento, Portugal: If the "Kursk" is completely flooded, that happen in the day of the accident or not?

Steve Rosenberg: We still don't know what caused this disaster but it does seem clear that most of the sub was flooded immediately or at least within minutes. That is the conclusion the experts have reached from studying the video evidence.

Mary, Canada: How the Norwegian divers, after determining that the escape hatch was flooded, could conclude that the entire submarine was flooded. Would it not be possible for there to be air pockets in other parts of the sub?

Steve Rosenberg: The divers were hoping yesterday to fine air pockets in the inner hatch because if they had found air there - it would have meant there could have been other areas of the sub with air pockets. To their dismay they found water - so the whole sub had been flooded. So experts concluded that without air pockets people could not survive.

Lucian Wischik, UK: Early on we were told that survivors tapped out messages in morse code on the hull. Was this really true, or an invention?

Steve Rosenberg: There has been so much contradictory information throughout this week - all I can say is that - tapping sounds were heard until the 14 August towards the back of the sub. It has been all very confused and it has been difficult to find out accurate information.

Pat van der Veer, Canada: To what extent was the military Russian "old guard" calling the shots in the Sub rescue?

Steve Rosenberg: This is one of the problems that the Russian media has been highlighting. Newspapers have been calling for the old Russian guard - people with the old Russian mentality - to be cleared out and this hasn't happened quickly enough.