As Russians grieved Monday for victims of the bloody assault on a concert hall near Moscow that killed at least 137 people, President Vladimir V. Putin was scheduled to meet with government officials to discuss the tragedy, the worst such attack in the capital in two decades.
The government appears to be stepping up efforts to pin the blame on Ukraine. On Sunday, hours after a district court arraigned four men suspected of carrying out the Friday night attack, the main evening news shows on Russia’s main television channels featured reports suggesting that Ukraine was responsible.
The main message was that Western countries were pushing a theory that a branch of the Islamic State was behind the attack, which took place at Crocus City Hall on the outskirts of Moscow, to shift blame away from Ukraine.
“The United States and Europe understand that any connection between Ukraine and the attack against Crocus City Hall would be suicidal for Kyiv and the whole anti-Russian alliance,” said one anchor, Dmitri Melnikov, in a report on Vesti Nedeli, the flagship weekly news show on Rossiya-1, the main state-owned television network.
The Islamic State has claimed responsibility for the attack. The United States has said that the assault was the work of an ISIS offshoot, the Islamic State in Khorasan, and that there is no evidence implicating Ukraine. Ukraine has denied any involvement.
On Monday, mourners streamed to take flowers to spontaneous memorials across the country. Many Russians were also going to hospitals to donate blood, state news media reported.
Three shopping malls belonging to the company that owns the concert hall said that they would be closed indefinitely. Emergency workers continued to clear the debris inside the concert hall.
But the coverage by Russian state news outlets reflected how the Kremlin seemed determined to muster its resources against what it apparently sees as its main enemy: Ukraine, backed by a coalition of Western states.
Russian investigators have not disclosed any evidence suggesting that the four suspects, men from Tajikistan who were migrant workers in Russia, have a connection to Ukraine.
In the news reports, Russian state television presented the location of their arrest — the Bryansk region of Russia that borders Ukraine — as evidence of Ukrainian involvement. The reports also suggested that Kyiv could have hired them to mount the attack.
In a statement about the tragedy, President Vladimir V. Putin said that the suspects “were heading toward Ukraine” and that “according to preliminary information, a window was prepared for them on the Ukrainian side to cross the state border.”
Dmitri S. Peskov, the Kremlin’s spokesman, said on Monday that Mr. Putin would meet with Russian government officials and the heads of the Moscow region to discuss unspecified measures that needed to be taken after the attack.
Mr. Peskov said he would not comment on the course of the investigation.
“We urge you to rely on the information that comes from our law enforcement agencies,” Mr. Peskov said.
The four suspects, according to their brief appearances in court, were foreign migrant workers who spoke little or no Russian. In videos of their appearances, they looked severely beaten, and videos of their being tortured during interrogation circulated widely on social media. One of the suspects, Muhammadsobir Z. Fayzov, 19, was rolled into the courtroom in a wheelchair.
Their appearance has reignited calls to further regulate labor migration into Russia. And Mikhail Sheremet, a lawmaker, told the state agency RIA Novosti that he would push for the reintroduction of capital punishment in Russia.