Germany, Kyiv's second biggest military backer behind only the United States, is itself being increasingly targeted by Russian spying and sabotage activities, they said.

"Whether we like it or not, we are in a direct confrontation with Russia," BND foreign intelligence chief Bruno Kahl told a parliamentary hearing.

President Vladimir Putin's long-term goal was to weaken the West, Kahl said, while a military clash with NATO was "becoming an option for Russia".

"In terms of personnel and material, Russian armed forces are likely to be capable of carrying out an attack against NATO by the end of the decade at the latest," Kahl said.

Kahl spoke at a hearing in the Bundestag alongside the heads of Germany's domestic and military intelligence services, who took turns to warn of the growing threat from Russia against the backdrop of the invasion of Ukraine.

"Russian espionage and sabotage in Germany are increasing, both qualitatively and quantitatively," domestic intelligence chief Thomas Haldenwang said.

He listed suspected sabotage activities, including a near miss involving an exploding package and a DHL cargo plane.

The parcel had burst into flames on the ground at the airport in Leipzig in July before it could be loaded onto the plane, in what Haldenwang called a "lucky accident".

"If it had exploded onboard during the flight, there would have been a crash and the debris could have hit all the people here in Germany who, openly or secretly, sympathise with Putin," he said.

- 'Real hurricane' -

Haldenwang said Russia was also engaged in disinformation campaigns, had deployed drones to spy on critical infrastructure and was looking to recruit people, including from the world of organised crime.

Moscow's campaign of disruption had grown from a storm to a "real hurricane" moving west, Haldenwang said, noting that Germany's eastern neighbours Poland and the Baltic states faced an even more "brutal" threat.

Germany has been shaken by several cases of alleged spying for Russia and alleged acts of sabotage since Moscow launched its full-scale invasion of Ukraine in 2022.

In April, investigators arrested two German-Russian men on suspicion of spying for Russia and planning attacks in Germany -- including on US army facilities -- to undermine military support for Ukraine.

Subsequently, a German military base was sealed off after a hole was discovered in the fence in a suspected act of sabotage, while trespassers have allegedly sought entry to NATO camps in the country.

The German armed forces had seen a "significant increase" in espionage and sabotage activities linked to Russia, the head of military intelligence Martina Rosenberg said at the parliamentary hearing.

Among the activities undertaken by Russia were "reconnaissance of German arms deliveries to Ukraine" as well as surveillance of military training and armaments projects, she said.

The trio of intelligence chiefs pleaded for more powers to counter Russian activities among other threats on German soil.

The intelligence services were "fighting fires on all sides", Haldenwang said, noting the threat posed by possible Chinese and Iranian-backed activities, as well as radical Islamists and the far right in Germany.