The death toll from the Moscow concert hall attack has increased to 143, Russian officials said.
Around 80 other people wounded in the siege by gunmen remain in hospital.
The Friday night massacre in Crocus City Hall, a sprawling shopping and entertainment venue on the north-western outskirts of Moscow, was the deadliest terror attack on the Russian soil in nearly 20 years. At least four men armed with automatic rifles shot at thousands of concertgoers and set the venue on fire.
The updated fatalities from Russia’s Emergencies Ministry did not state the number of wounded, but health minister Mikhail Murashko said earlier on Wednesday that 80 people were in hospitals and another 205 had sought medical treatment from the attack.
Russia’s Federal Security Service (FSB) said it had arrested 11 people the day after the attack, including four suspected gunmen.
The four men, identified as Tajik nationals, appeared in a Moscow court on Sunday on terrorism charges and showed signs of severe beatings. One appeared to be barely conscious during the hearing.
Russian officials, however, have insisted Ukraine and the West had a role, claims Kyiv vehemently denies. Ukrainian President Volodymyr Zelensky accused his Russian counterpart, Vladimir Putin, of trying to drum up fervour as his forces fight in Ukraine.
“We believe that radical Islamists prepared the action, while Western special services assisted it and Ukrainian special services had a direct part in it,” Mr Bortnikov said.
He repeated Mr Putin’s claim that the four gunmen were trying to escape to Ukraine when they were arrested, casting it as proof of Kyiv’s alleged involvement.
But that assertion was undercut slightly by Belarus’ authoritarian President Alexander Lukashenko, who said on Tuesday the suspects were headed for Ukraine because they feared tight controls on the Belarus border.
IS, which lost much of its territory following Russia’s military action in Syria after 2015, has long targeted Russia.
The group, which operates mainly in Syria and Iraq but also in Afghanistan and Africa, also has claimed several attacks in Russia’s volatile Caucasus and other regions in the past years. It has recruited fighters from Russia and other parts of the former Soviet Union.
On Monday, Mr Putin warned that more attacks could follow, alleging possible Western involvement. He did not mention the warning about a possible imminent terrorist attack that the US shared confidentially with Moscow two weeks before the raid.
Three days before the attack, Mr Putin denounced the US Embassy’s March 7 notice urging Americans to avoid crowds in Moscow, including concerts, calling it an attempt to frighten Russians and “blackmail” the Kremlin ahead of the presidential election.
Mr Bortnikov said Russia was thankful for the warning but described it as very general.