Moscow, Mar 23 (IANS): Urging the international community to stand with Russia, President Vladimir Putin on Saturday pledged to punish the perpetrators of the dastardly attack that killed 143 people and injured several others in a concert hall near Moscow.

In a televised address to the nation, the 71-year-old leader said the four gunmen, directly involved in the attack, were moving towards the country's border with Ukraine.

"We will be investigating this terrorist attack and we already have some results. All four perpetrators, directly involved in gunning people down, have been found and apprehended," the President said.

"They tried to escape... they were moving towards the border with Ukraine and we have data that suggests that they were about to be moved to the territory of Ukraine. Our investigators are working to find the orchestrators of this attack," he added.

So far, the Russian police have 11 suspects in custody, including all four gunmen, who were directly involved in carrying out the heinous attack.

The Islamic State took responsibility for the attack, saying its fighters attacked "a large gathering" on Moscow's outskirts and "retreated to their bases safely".

"We know what terror threat means, this is an attack against Russia, and we expect that other nations that share our pain will cooperate with us."

"We will stand united against this common enemy, no matter where it shows its ugly head. These terrorists have no nationality and there is only one future for them -- retribution," Putin, who was re-elected Russian President recently, said.

"Our common duty right now is to stand together, to stand united... and I believe, if we stand together, nobody can divide us, nobody can undermine our common strength," Putin said, adding that Russia has faced many challenges in its history but has always come out strongly.

Earlier, the Russian security agency, Federal Security Service (FSB), said the attackers were driving to the border.

"After committing the terrorist attack, the criminals intended to cross the Russian-Ukrainian border, and had appropriate contacts on the Ukrainian side," FSB said.

Kyiv reportedly said it had "nothing to do" with the attack, and called the attack a Russian "provocation", claiming that Moscow special services were behind it.