The number of victims of the attack in the concert hall in Moscow has risen to 140, reports the "Associated Press".
Russian officials indicated that one more of the victims died in hospital.
He was one of five people still hospitalized in "extremely serious condition" and doctors are "doing everything possible" to save them, said Russian Health Minister Mikhail Murashko.
A total of 80 people injured in the attack remain in hospital, and another 205 have sought outpatient medical care.
The Friday night bombing at the "Crocus City Hall" on the northwestern outskirts of Moscow was Russia's deadliest terrorist attack in nearly 20 years. At least four gunmen with assault rifles opened fire on thousands of concertgoers and set fire to the hall.
"Islamic State" claimed responsibility for the attack, and US intelligence said it had information to back it up. French President Emmanuel Macron indicated that France also had intelligence pointing to an ISIS organization as responsible for the attack.
Russia's Federal Security Service said it had arrested 11 people the day after the attack, including the four attackers. They are citizens of Tajikistan and appeared before a Moscow court on Sunday on charges of terrorism with signs of a brutal beating.
Russian officials, however, insist that Ukraine and the West played a role in the attack, a claim Kiev strongly denies. Ukrainian President Volodymyr Zelensky has accused his Russian counterpart Vladimir Putin of trying to stoke anger as his forces fight in Ukraine.
FSB chief Alexander Bortnikov also claimed that Western spy services may be involved. "We believe that radical Islamists prepared the action, Western special services provided assistance, and Ukrainian special services were directly involved in it," he pointed out.
He echoed Putin's claim that the four shooters tried to flee to Ukraine while in custody, which he said was evidence of Kiev's alleged involvement.
However, this claim was slightly undermined by the President of Belarus, Alexander Lukashenko, who said that the suspects headed to Ukraine because they feared strict border controls with Belarus.