Russia said on Thursday it had evidence the perpetrators of last week's massacre at a concert hall outside Moscow were linked to "Ukrainian nationalists," a claim that the United States called nonsense.

President Vladimir Putin and his security services continue to allege Kyiv and the West were involved somehow in last Friday's attack, despite an Islamic State affiliate having claimed responsibility.

Putin said on Saturday that 11 people had been detained after gunmen stormed the Crocus City Hall, setting the building alight and killing at least 143 people.

"As a result of work with the detained terrorists, examination of the technical devices seized from them and analysis of information on financial transactions, evidence of their links with Ukrainian nationalists has been obtained," Russia's Investigative Committee said on Thursday.

It alleged the suspects had received "significant amounts of money and cryptocurrency from Ukraine" and said another man "involved in financing the terrorists" had been identified and detained.

"Investigators will ask the court to remand him in custody," it said.

Ukraine and its Western allies have branded as absurd accusations they were involved.

"My uncle used to say ... that the best manure salesmen often carry their samples in their mouths," US National Security Council spokesman John Kirby told reporters on Thursday.

"Russian officials seem to be pretty good manure salesmen," Kirby said, denouncing what he called Russia's "nonsense propaganda."

The four suspected assailants – with bruises and cuts on their swollen faces – were dragged into a Moscow courtroom on Sunday, all of whom were from Tajikistan, Russian media reported.

Russia's FSB security service said it arrested the gunmen while they were trying to flee to Ukraine, a claim seemingly disputed by Belarusian strongman Alexander Lukashenko, who said they were headed for his country first.

Islamic State jihadists have said several times since Friday that they were responsible, and IS-affiliated media channels have published graphic videos of the gunmen inside the venue.

Kremlin spokesman Dmitry Peskov gave no indication on Thursday that Putin planned to visit the family members of those killed.

The Russian leader was seen lighting a candle for the victims at a Moscow church last week, but has not visited the scene of the massacre or publicly met with any victims.

"If any contacts are necessary, we will inform you accordingly," Peskov said, when asked if Putin planned to meet family members of the dead.

He also said Putin did not plan to visit Crocus City Hall, where rescuers had for the past week been searching the rubble for bodies.

"In these days it would be completely inappropriate to carry out any fact-finding trips, because this would simply interfere with the work," he said. (AFP)