The 28-year-old man charged with carrying out a bomb attack on Borussia Dortmund's team bus last year has pleaded guilty at the city's district court.

The man, known only as Sergej W, admitted causing an explosion in order to profit from a significant drop in the Bundesliga club's shares.

He read out a statement on the second day of the trial in which he said: "I deeply regret my behaviour. I can't explain to myself what I did there.

"I did not want to injure any people, and I did not want to kill anyone. I only wanted to feign a severe attack."

The defendant, led into the court in handcuffs, carried a laptop and an envelope containing his statement.

He has been charged with 28 counts of attempted murder, causing an explosion and two counts of serious bodily harm following the attack on the team bus ahead of the Champions League home match against Monaco in April.

Prosecutors said the German citizen, born in Russia, was a cold-blooded person, acting out of greed to profit from a drop in the share price of the only German football club listed on the stock market.

While Sergej W admitted having caused the explosion, he said in his statement that the three bombs used "were constructed to not cause bodily harm."

He said: "I only wanted Borussia Dortmund to crash out of the Champions League."

Speaking to reporters, Dortmund's lawyer Alfons Becker said he did not think it "conceivable" that such an attack "can be controlled in a way that it only terrifies others."

Dortmund players at the scene of the attack on their team bus. AP Photo/Martin Meissner

Judge Peter Windgatter listened as Carl W Heydenreich, one of Sergej W's two lawyers, said in a statement that the attack had been planned since early 2017.

He said the defendant hoped to establish a "realistic scenario" of a terror attack, laying a false trail to Islamist extremists by placing a letter of confession at the scene.

The attack would then lead to "a postponement of the Champions League match and a sustainable economic weakening of BVB by crashing out of the competition."

The match was postponed until the following day and Dortmund lost both legs of the tie.

Heydenrich implied that Sergej W could have been driven by suicidal thoughts, adding: "He no longer saw any sense or fulfilment in his life.

"One motive was to leave something to his parents should he depart this life."

Dortmund CEO Hans-Joachim Watzke said some of the players on the bus during the attack had suffered "post-traumatic stress."

Defender Marc Bartra sustained a broken bone in his wrist, while a motorcycle police officer accompanying the team bus suffered an ear injury.