DUESSELDORF (Reuters) -Berlin is taking reports of a plot to assassinate the chief executive of arms manufacturer Rheinmetall very seriously and will not be cowed by Russian intimidation, the German government said on Friday.

CNN and the New York Times on Thursday reported that U.S. intelligence had discovered a Russian plan to kill Armin Papperger, CEO of a company that has produced artillery shells and military vehicles for Ukraine.

The plot was one of a series of Russian plans to assassinate defence industry executives across Europe supporting Ukraine's war effort, CNN reported. Washington informed Germany and German security services were able to protect Papperger, it said.

"We will not allow ourselves to be intimidated by Russia and will continue to do everything we can to prevent Russian threats in Germany," Germany's Interior Minister Nancy Faeser said.

One of the world's biggest producers of artillery and tank shells, Rheinmetall has not directly confirmed the reports but said in a statement that "necessary measures are always taken" for security, in regular consultation with security authorities.

The Kremlin denied the reports as fake, based on anonymous sources, and said they could not be taken seriously.

German defence group Hensoldt, which produces radar technology for the IRIS-T air defence system used in Ukraine, said it was reassessing safety measures.

The weapons division for Diehl, the German company that manufactures the IRIS-T and also produces ammunition, said it was monitoring the situation closely and would adapt its security measures if necessary.

In April the German authorities arrested two German-Russian nationals on suspicion of plotting sabotage attacks, including on U.S. military facilities, in an attempt to undermine military support for Ukraine.

Germany also accuses Russia of the murder of an exiled Chechen-Georgian dissident in Berlin's Tiergarten park in broad daylight in 2019. The assassin Vadim Krasikov is serving a life sentence, and the court ruled that Russia was responsible for state terrorism.

"The Tiergarten murder already showed that Russia does not shy away from assassination attempts here either. We take reports of further murder plans very seriously," said Justice Minister Marco Buschmann.

"Our security forces are well positioned. Russia wants to weaken us, but it will not succeed: we are capable of defending ourselves."

The Washington Post this week, citing Kremlin documents obtained by a European intelligence service, said Russia was making extensive efforts to find recruits for sabotage attacks.

The documents show that in July 2023, Kremlin political strategists studied the Facebook profiles of more than 1,200 people they believed were workers at two major German plants -- Aurubis and BASF in Ludwigshafen -- to identify employees who could be manipulated into stirring unrest, the report said.

The Kremlin said the allegations of Russian sabotage activity were "no more than a stoking of Russophobic hysteria", the report said.

FEARS OF MORE ATTACKS

Rheinmetall's company value and Papperger's public profile have surged with a defence spending boom after the Russian invasion.

Papperger has repeatedly advocated for more arms deliveries to Ukraine and urged the German government to increase defence spending in order to finance them.

In May 2023, it said it had set up a joint venture with Ukrainian state-owned conglomerate Ukroboronprom to build and repair tanks in Ukraine.

Russia's former President Dmitry Medvedev, a close ally of current President Vladimir Putin, said Russia would retaliate by hitting any facility Rheinmetall set up in Ukraine.

Papperger is accompanied by security guards whenever he appears. Questions over his personal safety were already in focus this year when his garden house was set on fire by what tabloid newspaper Bild said were far-left activists.

Speaking to reporters in May about the incident, Papperger said he was grateful he was being guarded by security personnel.

"There are probably some people in the world who don't like what I do. In that respect, the Federal Republic of Germany is making sure that I am safe. I am grateful for that too," he told reporters at the time.

"Thank God I wasn't there," he said of the attack on his garden house. "There are just a lot of crazy people in the world. The use of violence is something that I cannot accept. I am working with all my strength to ensure that we can defend ourselves against people who use violence. Some people don't like that."

The Financial Times in a report said the levels of protection for Papperger were now similar to those for Chancellor Olaf Scholz.

The vice-chair of the parliamentary intelligence oversight committee, conservative lawmaker Roderich Kiesewetter, warned of possible further Russian attacks in Germany.

The foiled assassination attempt on Papperger should "not obscure the fact that Russia has other targets in its sights and is using espionage, sabotage and targeted killings," Kiesewetter told Handelsblatt.

"It is not for nothing that Russia was designated a terrorist state by a German court."

(Reporting by Matthias Inverardi, Alexander Hübner, Miranda Murray, Rachel More, Matthias Williams; writing by Matthias Williams; editing by Peter Graff and Jason Neely)

By Matthias Inverardi and Matthias Williams