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.