Here is a chronology of the key dates in the four-year long conflict with Russia:

1999

Oct 1: Russian forces enter Chechnya for the first time since the end of the 1994-1996 war, forcing the rebels to abandon almost a third of the country.

Oct 29: 50 people are killed as refugees fleeing towards Ingushetia are bombed.

Nov 12: Russian forces take the second Chechen town of Gudermes without resistance.

Nov 25: Start of the battle for Grozny, defended by 2000 separatists.

2000

Feb 1: The rebels say they are withdrawing from Grozny, followed five days later by an announcement by Russian President Vladimir Putin that the Chechen capital has been liberated.

Feb 11: Chechen president Aslan Maskhadov calls an all-out guerrilla war.

Feb 23: Human Rights Watch says more than 60 civilians were massacred in Grozny earlier in the month.

Feb 29: Russian forces seize Shatoi the last major rebel stronghold in the southern mountains.

June 8: Putin places Chechnya under direct presidential administration and names former mufti Akhmad Kadyrov as the leader of the pro-Russian administration.

2001

Jan 22: Putin gives the Russian security services, the former KGB, control of operations in Chechnya. 

More than 40 people died in a bomb
attack on a Russian train

April 14: Putin makes his first visit to Chechnya since his election in March.

July: Russian prosecutors open an inquiry into a suspected "abuse of power" by Russian forces, as Putin acknowledges "irregularities" and "abuses" by the army.

Nov 19: First direct talks between envoys from Putin and Maskhadov, but the negotiations end without result.

Dec 30-Jan 1: More than 200 killed in a Russian operation east of Grozny

2002

Aug 19: A Russian Mi-26 helicopter is shot down by rebels, killing 121 people.

Oct 24: Rebels take hundreds of people hostage in a Moscow theatre and demand an end to Russian military operations in Chechnya. A total of 130 civilians and 41 Chechen guerrillas die in the rescue operation.

Dec 27: About 80 people are killed when rebels drove two explosives-packed vehicles into the Chechen administration headquarters, destroying Russia's symbolic seat of power there.

2003

March 26: Nearly 90 percent of people in Chechnya vote in favour of rule from Moscow in a referendum even though hopes of ending the decade-long separatist conflict appear as remote as ever.

 Chechen separatists were killed
after taking hostages in a theatre

April 2: The Council of Europe calls for the creation of an international tribunal to try war crimes committed in Chechnya.

May 14: A suicide attack on a government building in Chechnya kills 60 people, one of the deadliest single attacks since conflict between separatist rebels and federal troops broke out.

May 16: Another suicide bomb attack carried out by a woman during a religious parade in Chechnya kills 18. Akhmad Kadyrov, who was present, survives.

July 5: Suicide attack on a rock concert kills 20 people in Moscow.

July 25: Russian army colonel receives a 10-year prison sentence for killing an Chechen teenage girl in Chechnya.

Oct 5: Akhmad Kadyrov elected president of Chechnya in controversial poll, winning over 80 percent of the vote.

Dec 5: More than 40 people die in a bomb attack on a Russian commuter train just north of Chechnya.

2004

Feb 6: A powerful bomb rips through a packed Moscow subway train during the morning rush hour, killing 41 people.

May 9: Akhmad Kadyrov is killed in a blast in a stadium in Grozny. At least 31 others are killed and dozens of others injured.