The commander of Russian forces in the region was among many others injured by the assassination, apparently concealed in the stadium's structure, at annual celebrations marking Moscow's 1945 victory over Nazi Germany.

"Kadyrov passed away on May 9 on the day of our national holiday," Putin was quoted yesterday by the Kremlin as saying after meeting the official's son, Ramzan.

Valery Baranov, commander of Russian forces in the region, underwent surgery for serious wounds at a military hospital.

There were scenes of pandemonium at the "Dinamo" stadium after the blast with people running around in panic and smoke rising from the wreckage of the stands.

Television showed a man carrying a young boy, unconscious and bleeding from the mouth, down the terraces. Another old man, blood pouring through a bandage on his head, was being helped away by two men.

Reports said about 20 people were wounded.

"The bomb was placed inside a concrete part of the stadium," said Khamid Kadayev, Chechnya's deputy interior minister, speaking on television from the scene of the blast.

He said this was why the bomb had not been detected on Saturday night and yesterday morning when the stadium was swept by security officials before Victory Day celebrations.

Television reports suggested the bomb may have been planted in the stadium during reconstruction work over the past three months.

Itar-Tass news agency quoted an interior ministry spokesman as saying five people had been detained in connection with the attack. It gave no details.

Kadyrov, bearded and thickset, once called on Chechnya's Muslims to fight a jihad (holy war) against the Russian army but he later made his peace with Moscow and is now viewed by Chechen rebels as a traitor.

BLAST TARGETED VIP AREA
The attack on the stadium at what would have been a high-security event, celebrating a major occasion in Russian history, dealt an enormous blow to Putin's efforts to restore order in the north Caucasus region.

Putin, who has several times declared the war in Chechnya to be effectively over, has made his hardline policy in the region a key part of his domestic policy. He told World War Two veterans after the attack:

"There can be no doubt that retribution is unavoidable for those whom we are fighting today. It will be unavoidable for terrorists."

The blast appeared to target the VIP area of the stadium.

Kadyrov had been the lynchpin of Putin's attempts to restore firm Russian rule in Chechnya. He was elected last October, virtually unchallenged, to build an administration capable of establishing full Russian authority.

Interfax news agency said Sergei Abramov, at present Chechen prime minister, would take over as acting president.

The attack appeared to be the most audacious launched by Chechen rebels on Russian forces and the administration in Chechnya since Russian troops reoccupied the area in 1999.

Victory Day is a major national celebration in Russia of enormous symbolic importance in the country.

The Grozny ceremonies were mirrored by festivities throughout the country, including a marchpast on Moscow's Red Square overseen by Putin.

Chechen rebels have in the past targeted official events and public gatherings for attacks.

A Reuters reporter was among the injured.