By Guy Faulconbridge
MOSCOW (Reuters) -A powerful ally of President Vladimir Putin on Friday accused the United States of coordinating with Ukraine to kill two pro-war nationalists in Russia and to carry out attacks on critical national infrastructure in an effort to undermine stability.
There was no immediate U.S. response to the allegations from Nikolai Patrushev, secretary of Russia's Security Council, which is chaired by Putin. Washington has previously denied involvement in at least one of the killings he mentioned.
Putin has accused the West of unleashing a proxy war aimed at toppling him and carving up Russia's vast natural resources following Russia's invasion of Ukraine last year, something Moscow calls "a special military operation".
A series of showcase attacks and mysterious assassinations inside Russia, far from the front lines in Ukraine, have raised concerns over domestic security, even more so after a drone attack on the Kremlin itself.
Darya Dugina, the daughter of a prominent Russian nationalist, was killed in a car bomb in August; pro-war blogger Vladlen Tatarsky, whose real name was Maxim Fomin, was killed in a bomb last month; and nationalist writer, Zakhar Prilepin, was wounded in a car bomb earlier this month.
Russia also accused Ukraine of attacking the Crimean Bridge last October and accused the West of being behind blasts on the Nord Stream gas pipelines in September.
Patrushev was cited by the state TASS news agency as saying all the attacks "were planned and carried out with the coordination of the U.S. special services".
"The terrorist attacks committed in Russia are accompanied by an information campaign prepared in advance in Washington and London, designed to destabilise the socio-political situation, and to undermine the constitutional foundations and sovereignty of Russia," TASS quoted Patrushev as saying.
The United States and its allies, who cast the invasion as an imperial-style land grab, say they want Ukraine to defeat Russia, the world's biggest nuclear power.
The State Department did not immediately reply to a request for comment on Patrushev's remarks.
U.S. intelligence agencies believe parts of the Ukrainian government authorised the attack that killed Dugina, the New York Times reported in October.
Although President Joe Biden has warned that a direct military confrontation between the NATO military alliance and Russia would trigger World War Three, the Kremlin says the West is already fighting against Russia.
The United States and Britain have denied Russian claims they were involved in the sabotage of the Nord Stream pipelines. Ukraine has never claimed responsibility for the attack on the Crimean Bridge.
Washington said earlier this month it was a lie that the United States was behind the drone attack on the Kremlin.
As a former Soviet spy who has known Putin since the 1970s, Patrushev - who has accused the "Anglo-Saxons" of sabotaging Nord Stream in what he has called a terrorist attack - is seen by Western diplomats as having a major influence on the Russian leader.
Patrushev's pronouncements give an insight into thinking at the Kremlin's top levels, they say.
"The risks of terrorist acts, including the use of unmanned aerial vehicles, at critical and potentially dangerous facilities have increased significantly," Patrushev said.
He said Ukrainian saboteurs within Russia were likely planning further attacks.
(Editing by Andrew Osborn and Alex Richardson)