MOSCOW, March 29. /TASS/. The investigation into the terrorist attack on the Crocus City Hall venue outside Moscow is in full swing, and it is making good headway, Russian Foreign Minister Sergey Lavrov said in an interview with the Izvestia daily.

"Russian President Vladimir Putin gave a tough, comprehensive assessment of what happened. He stressed that the investigating authorities, the Prosecutor General’s Office and intelligence agencies had received all necessary instructions. Active work is underway, which has produced rather quick results," the top diplomat noted.

He reiterated the Russian leader’s remark that "all those who plotted, organized, financed and carried out the terrorist attack will be justly punished."

Lavrov also added that during their non-public contacts with Russia, Western officials and diplomats have been ‘suspiciously assertive’ while assuring Russia that Ukraine has nothing to do with the Crocus City Hall attack, but Moscow cannot rule out Kiev’s involvement at this point.

"The West is suspiciously assertive as it tries to convince us, not only publicly but also in their contacts with our diplomatic missions, that we should not suspect Ukraine, without explaining why. From the perspective of common sense, pondering the question of who benefits from this (this question invariably comes up whenever there is a crime to solve), we cannot rule out Ukraine," Lavrov said.

In his words, the West is trying hard to convince everyone that ISIS (Islamic State terrorist organization, outlawed in Russia) is behind it and there is no point in suspecting anyone else, above all Ukraine.

"They mention that country directly and regularly to the point of becoming obsessive about it, and keep saying Ukraine is not involved," he said.

"We have said many times that we will wait for the investigation to complete before drawing final conclusions. The investigators are still working on evidence, and new circumstances are coming to light, but we simply cannot ignore obvious theories, especially so as the perpetrators were detained near the Ukrainian border," Lavrov continued.

He doubted remarks by Head of Ukraine’s Military Intelligence Agency Kirill Budanov (added to the list of extremists and terrorists in Russia) about his country’s non-involvement.

"No one would believe what this person has to say," he said, citing Budanov’s earlier threats to Russian speakers in Ukraine.

On the evening of March 22, a terrorist attack targeted the Crocus City Hall music venue in Krasnogorsk, Moscow Region, just outside the Moscow city limits. At least 143 people were killed. According to the latest data, some 360 people were injured, 205 of whom received medical assistance.

Eleven people suspected of involvement in the terrorist attack have been apprehended, including the four gunmen, who were arrested in the Bryansk Region, southwest of Moscow, as they attempted to flee to Ukraine across the nearby border.

President Vladimir Putin said in a televised address that, according to preliminary information, the Ukrainian side had prepared "a window" at the border especially for the terrorists to cross undetected. He promised to identify and punish all those who were behind the attack on Crocus City Hall.