German intelligence believes a cache of guns found in the woods near Berlin last year was for carrying out assassinations on behalf of Russia, reports say.

Germany's Interior Minister Alexander Dobrindt said federal prosecutors were investigating a suspect in Romania over suspicions of espionage and "the preparation of a serious act of violence threatening the state".

While refusing to confirm reports of Russian links to the cache, Dobrindt said he could not rule out "the involvement of foreign powers".

For months security agencies have warned that Russian intelligence services are planning assassinations in Germany, possibly targeting defence industry executives or opposition figures in exile.

Dobrindt said that last October Germany's domestic intelligence agency became aware of a possible weapons cache in the woods on the outskirts of Berlin.

Officials located the stash with the help of the Berlin State police, and found two handguns and ammunition.

The German security authorities suspect the weapons and ammunition found were intended for use in attacks.

Reports in German daily newspaper Süddeutsche Zeitung and the public broadcasters NDR and WDR say the cache was to facilitate targeted killings on behalf of Moscow.

Dobrindt said after the guns were rendered inoperable, the weapons cache was placed under surveillance for months but nobody was seen approaching it.

"This case demonstrates that we are operating under a high threat level," Dobrindt said.

The minister said prosecutors were investigating a suspect in Romania, who is being held in connection with planned parcel bomb attacks there. He said this would be taken into account when it came to a possible extradition.

He described the suspect as a "low-level agent", and declined to disclose his nationality.

Several similar operatives had been detained so far this year, he said, including one person from Kazakhstan.

The investigation follows previous accusations of Russian attacks on German soil.

In 2024, German political figures reacted angrily to a CNN report that Russia had plotted to kill the head of Germany's biggest arms company Rheinmetall, Armin Papperger.

In 2021 a German court jailed Russian national Vadim Krasikov for life for a murder in a Berlin park and said it had been ordered by Moscow. Krasikov was later freed in a prisoner swap.