Russia has arrested three suspected Ukrainian intelligence agents and accused one of them of planning a bomb attack, the Interfax news agency cited the Federal Security Service (FSB) as saying Thursday.

The other two people in custody are suspected of gathering intelligence about strategic sites in Russia, the report said. According to FSB, the detentions came as a result of an intelligence operation in three regions of Russia. The agency said sabotage activities of the Ukrainian special services were suppressed.

Two agents of The Security Service of Ukraine (SBU) Zinovy ​​Kovyl and his son Igor, as well as an agent of the Main Intelligence Directorate of the Ministry of Defense of Ukraine (GUR MOU), Alexander Tsilyk, were detained.

"We have received materials confirming the terrorist aspirations of the Ukrainian military intelligence to facilities on the territory of our country," the Special Communications and Information Service of the Federal Protective Service of the Russian Federation or Spetssvyaz said Thursday. It claimed that two of the alleged spies "traveled to Russia to collect information and take photographs and videos of strategically important enterprises and objects of transport infrastructure."

The pair confessed to having been recruited by the SBU, the FSB said, which offered them a fee of $10,000. The third Ukrainian, who planned to carry out an attack, "was recruited and acted on the instructions" of a top Ukrainian intelligence officer, the FSB said.

"The attack was planned to be carried out by detonating two improvised explosive devices with a total mass of 1.5 kilogrammes in a TNT equivalent," the FSB said in a statement. He "was detained red-handed with weapons of destruction on his way to the scene of the crime," the agency added. It did not specify where or when the attack was to take place.

**editors_pick[90364-Ukraine urges NATO to ready sanctions against Russia amid war threat]**

In addition, the report said that in November the court found a senior officer of GUR MOU, Capt. Sergei Shvidenko, guilty of preparing crimes against the security of Russia and sentenced him to 6 1/2 years in a strict regime colony. In July of this year, Shvidenko was arrested and taken into custody.

"The investigation fully proved the guilt of the ex-employee of the military intelligence of Ukraine. During the investigation, Shvidenko gave detailed confessions about the organization of sabotage on the territory of Russia and said that the operation was led by his immediate superior – Colonel Nikolai Bogdanovich Spodar, who headed the operational department," Spetssvyaz said.

Operational search activities and investigative actions to suppress the intelligence and sabotage activities of the Ukrainian special services on the territory of the Russian Federation continue, the special service emphasized.

Thursday's detentions come amid Ukrainian and Western concerns over a buildup of Russian troops near Ukraine. The tensions between the two countries have been simmering since May when Russia started to move massive military force to the Ukrainian border. The move sparked worldwide condemnation and raised questions over the security of Ukraine and Western countries.

Ukrainian President Volodymyr Zelenskyy said last week that his country’s intelligence service had uncovered plans for a Russia-backed coup. Zelenskyy said that it allegedly involves one of Ukraine's richest oligarchs.

Both the oligarch and the Russian government rejected the allegations. In Nantucket, Massachusetts, where he is spending a holiday weekend, United States President Joe Biden expressed concern at the talk of a coup and renewed U.S. support for Ukraine's sovereignty and self-government.

At a news conference in Kyiv, the Ukrainian capital, Zelenskyy said he received information that a coup was being planned for next Wednesday or Thursday. He did not give many details to back up his allegation but pointed to a suspected role of Ukraine's richest oligarch, Rinat Akhmetov.

The president said that Ukrainian intelligence has audio recordings of an alleged meeting between Russian and Ukrainian officials discussing a plan for a coup allegedly funded by Akhmetov, whose fortune is estimated at $7.5 billion.

Zelenskyy refused to disclose further details about the alleged coup, saying only that he doesn't plan to flee the country. Kremlin spokesperson Dmitry Peskov rejected the allegations in comments to journalists in Moscow on Friday.

"Russia had no plans to get involved," Peskov said, according to The Associated Press (AP). "Russia never does such things at all."

Akhmetov called Zelenskyy's allegations "an absolute lie."

"I am outraged by the spread of this lie, no matter what the President's motives are," Akhmetov said in a statement, relayed to the AP by his spokesperson Anna Terekhova.

Asked about the alleged coup plans, the U.S. State Department's top official for European and Eurasian affairs, Karen Donfried, said: "We are in touch with the Ukrainian government to discuss this further, and we're working to obtain additional information."

Biden told U.S. reporters he expected to talk to Putin and Zelenskyy, "in all probability."

Volodymyr Fesenko, a Kyiv-based political analyst and head of the Penta Center think tank, told the AP that Zelenskyy targeted Akhmetov after a "proper information war" was waged against the president over the last two months on TV channels the oligarch owns.

In the last three decades, relations between Russia and the West have soured to their worst level since the end of the Cold War. Ukraine says Russia has deployed more than 10,000 troops near their long shared border.

Moscow accuses Kyiv of pursuing its own military build-up. It has dismissed as inflammatory suggestions it is preparing for an attack on Ukraine but has defended its right to deploy troops on its own territory as it sees fit.

U.S. Defense Secretary Lloyd Austin on Thursday suggested any U.S. response to Russia's actions toward Ukraine would be carried out in conjunction with the international community, as he called on Moscow to be transparent about its military buildup.

Austin, during a visit to South Korea, also voiced hope that the U.S. and Russia could work to "resolve issues and concerns and lower the temperature in the region."

U.S. Secretary of State Antony Blinken has warned Moscow to pull back its troops from the Ukrainian border, saying a Russian invasion would provoke sanctions that would hit Moscow harder than any imposed until now. Asked whether fallout on Russia would be strictly economic, Austin declined to answer directly, saying only that the "best methods" would be used.

"Whatever we do will be done as a part of an international community. The best case though is that we won't see an incursion by the Soviet Union into the Ukraine," Austin said, accidentally calling Russia the former Soviet Union.