Putin vows retribution for Moscow attack that killed more than 143

Russia suggests Ukraine link even as ISIS claims responsibility

Russian President Vladimir Putin on March 23 called the attack on a concert hall that killed more than 143 a "barbaric terrorist act" and vowed harsh retribution to all those involved.

In a televised address, he said all four gunmen had been arrested before they had a chance to cross the border into Ukraine.

"I am speaking to you today in connection with the bloody, barbaric terrorist act, the victims of which were dozens of innocent, peaceful people," Mr Putin said in his first public remarks since the attack. "All four perpetrators of the terrorist attack who shot and killed people have been detained. They were travelling towards Ukraine where they had a window to cross the border." Russian investigators said on March 23 the death toll had risen to more than 143 from an earlier figure of 115.

"While clearing the debris in the Crocus City Hall concert hall, the number killed as a result of the terrorist attack rose... Search operations are continuing," the Investigative Committee said.

The attack, which saw the concert hall set ablaze, has been claimed by the Islamic State in Iraq and Syria (ISIS) but the Russian authorities have not mentioned this.

"Terrorists, murderers, non-humans will face the unenviable fate of retribution and oblivion," said Mr Putin, who declared March 24 a day of national mourning across Russia.

The ISIS militant group said on March 23 that four of its fighters carried out the attack.

"The attack was carried out by four (ISIS) fighters armed with machine guns, à pistol, knives and firebombs," it said on one of its Telegram channels, adding that the attack was part of "the natural context of the raging war" with "countries fighting Islam".