The two, identified only as Dieter S and Alexander J in line with German privacy rules, were arrested on Wednesday in the Bavarian city of Bayreuth, federal prosecutors said on Thursday.

They said Dieter S had been discussing possible acts of sabotage in Germany with a person linked to Russian intelligence since October, and the main aim was to undermine military support given by Germany to Ukraine.

The suspect declared himself willing to carry out bombing and arson attacks on infrastructure used by the military and industrial sites in Germany, prosecutors said in a statement.

He gathered information on potential targets, including US military facilities, they said.

Alexander J allegedly helped him to do so starting in March at the latest, while Dieter S scouted out some of the sites, took photos and videos of military goods and passed the information to his intelligence contact.

A judge on Wednesday ordered Dieter S kept in custody pending a possible indictment.

Alexander J was due to make a closed-doors court appearance on Thursday.

Dieter S also faces separate accusations of belonging to an armed unit of pro-Russian separatist forces in the Donetsk region of eastern Ukraine between December 2014 and September 2016.

Germany has become the second-biggest supplier of weapons to Ukraine after the United States since Russia started its full-scale invasion of Ukraine more than two years ago.

The US has a large military presence in Germany.

Australian Associated Press