TIMELINE: Major Russian naval accidents since 1991

(Reuters) - Twenty people were killed and 21 injured in an accident aboard a Russian nuclear submarine, the navy said on Sunday.

It is the worst accident on a nuclear submarine since the 2000 sinking of the Kursk.

Below is a timeline of Russia's main naval accidents since the collapse of the Soviet Union in 1991:

* Aug 12, 2000 - The Russian Oscar-II class submarine Kursk with 118 crew members sinks to the bottom of the Barents Sea after possibly a collision and two explosions on board.

* June 16, 2000 Toxic fuel leaked from a ballistic missile and poisoned several servicemen at a naval base in Russia's Far East. * August 28, 2003 - Russia's K-159 nuclear submarine sank while being towed to a shipyard. Nine crew were killed.

* February 2004 - Dressed in full naval uniform Russian President Vladimir Putin traveled to the Arctic to watch naval exercises but the focus -- a ballistic missile launch -- failed. * August 2005 - The British navy rescued seven Russian sailors trapped in a sunk mini-submarine off Russia's Pacific coast. * September 6, 2006 - Fire on board the Viktor-3 class Russian navy submarine St. Daniel of Moscow, moored near the Finnish border, kills two crew members. A few hours later a missile launch failed.

* November 8, 2008 - Twenty people died and 21 were injured on board the Nerpa, classified by NATO as an Akula-class attack submarine, when its fire extinguishing systems unexpectedly went off during sea trials in the Pacific.

(Compiled by Guy Faulconbridge and Dmitry Solovyov; Editing by Angus MacSwan)