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Vladimir Putin said that Russian security services had arrested four men who carried out a terror attack on a concert hall near Moscow.

The men are understood to be among a total of 11 people detained in connection with Friday's

attack, which killed at least 133 people and wounded many more.

Islamic State claimed responsibility for the rampage, sharing an image of the perpetrators on

telegram, a messaging platform. American officials who warned Russia of an

imminent attack two weeks ago said they had no reason to doubt the claim's credibility.

The attack is the worst terrorist incident to take place in Russia for decades. In his address

Mr Putin made no mention of Islamic State's involvement, promising to punish everyone

who stands behind the terrorists.

He tried to connect the attackers to Ukraine and claimed they were captured while fleeing

to the border.

Ukraine firmly denied any involvement.

Demetro Kuleba, the country's foreign minister, dismissed Mr Putin's remarks as a provocation

...