French Interior Minister Gerald Darmanin said that France has a very efficient intelligence system that allows law enforcement agencies to prevent terrorist attacks in the country almost every month.

"Fortunately, we have an extremely efficient intelligence system. We prevent terrorist attacks almost every month," Darmanin told reporters on Monday.

He added that some of the terrorist attacks prevented in France were prepared by the Islamic State terrorist group (IS or ISIS, banned in Russia), in particular at the end of 2022 in Strasbourg.

The United States has blamed a branch of ISIS, known as ISIS-Khorasan (banned in Russia as a terrorist), for the Crocus City Hall attack.

Meanwhile, the Russian Federal Security Service (FSB) has said that the four main suspects in the terrorist attack had contacts in Ukraine and were planning to cross the Russian-Ukrainian border when they were detained in Russia's Bryansk Region.

Russian President Vladimir Putin has also said that all four were heading for Ukraine, where, according to preliminary data, a "window" was prepared for them to cross the border.

Kremlin spokesman Dmitry Peskov stated that the Russian authorities had not commented on information about the possible involvement of the ISIS group in the terrorist attack, as the investigation was still underway and no official scenario had been put forward.

A shooting occurred last Friday in the Crocus City Hall concert venue in the city of Krasnogorsk, just outside Moscow, followed by a massive fire.

A Sputnik correspondent who witnessed the attack reported that a number of gunmen in camouflage broke into the music hall, shooting people point-blank and throwing incendiary bombs.

The Russian Investigative Committee said that at least 139 people were killed as a result of the terrorist attack.

Eleven people were detained in connection with the events, including four believed to be directly involved in the terrorist attack, the Russian Federal Security Service (FSB) said.

The four main suspects in the case were detained in the Russian region of Bryansk, which borders Belarus and Ukraine, the FSB added.

They were charged with terrorism and ordered to be held in pretrial custody until May 22, Moscow's Basmanny District Court said. All of them are from Tajikistan and could face a life sentence in prison.

The Moscow-area concert hall terrorist attack is the deadliest in Russia in nearly 20 years.

(With UNI inputs)