This is what the man's lawyers told German media.
The man, who is said to have been an officer in a special unit in the Ukrainian military, was arrested in Italy in August last year and later extradited to Germany.
Leaks were discovered in September 2022 in the Nord Stream 1 and 2 gas pipelines, which run from Russia to Germany along the bottom of the Baltic Sea. It was later confirmed that the pipelines had been blown up.
The man is suspected of having had a leading role in the group - which also included a captain, an explosives expert and four deep-sea divers - that carried out the sabotage.
The group is accused of attaching four timed explosive devices to gas pipelines near the Danish island of Bornholm.
Süddeutsche Zeitung describes the evidence against the man as extensive, as he allegedly told relatives and acquaintances about the sabotage in telephone conversations.
The incident is being investigated in Germany because the consequences of the explosions also had an impact on German territory.
Another suspect was arrested in Poland in September. However, Polish authorities rejected a German extradition request and the Ukrainian citizen was later released.
