The suspect in the Borussia Dortmund bus attack took out a five-figure loan to bet on the stock drop caused by last week’s bombing, German prosecutors have confirmed.

A German-Russian man was been arrested by police in the early hours of Friday morning following a raid by a police tactical response unit in the Tuebingen area, 30km south of the city of Stuttgart and 450km south of Dortmund, and accused of carrying out the bombing of the Borussia Dortmund team bus ahead of their Champions League quarter-final first leg last Tuesday.

The man, identified only as Sergej W under German law, has been charged with attempted murder, causing an explosion and serious bodily harm after three bombs exploded next to the bus, leaving Dortmund defender Marc Bartra with arm injuries that required surgery and also injuring a policeman.

Borussia Dortmund Team bus attack Show all 8 1 /8 Borussia Dortmund Team bus attack Borussia Dortmund Team bus attack Police stand near team bus of the Borussia Dortmund football club after it was damaged in an explosion in Dortmund, Germany Getty Images Borussia Dortmund Team bus attack Team bus of Borussia Dortmund is seen on a street after it was hit by three explosions in Dortmund, Germany EPA Borussia Dortmund Team bus attack According to reports, Borussia Dortmund's team bus was damaged by three explosions, as it was on its way to the stadium ahead of the UEFA Champions League soccer match between BVorussia Dortmund and AS Monaco EPA Borussia Dortmund Team bus attack Police escort Dortmund's players after the team bus of Borussia Dortmund had some windows broken by an explosion some 10km away from the stadium prior to the UEFA Champions League 1st leg quarter-final football match BVB Borussia Dortmund v Monaco in Dortmund, western Germany Getty Images Borussia Dortmund Team bus attack The match was postponed after a explosion targeted the Borussia Dortmun football team Rex Borussia Dortmund Team bus attack Police cars stand in front of the main entrance of the Dortmund training ground as Dortmund's players arrive one by one in their cars in Brackel, one day after the explosives attack on the Borussia Dortmund team bus prior to the UEFA Champions League 1st leg quarter-final football match BVB Borussia Dortmund v Monaco Getty Images Borussia Dortmund Team bus attack Fans hold posters 'You'll never walk alone' when Dortmund player Pierre-Emerick Aubameyang leaves the training ground of the team in Dortmund, western Germany, AP Borussia Dortmund Team bus attack A team bus arrives at the training grounds of Borussia Dortmund in Dortmund, German AP

After questioning the validity of a letter found at the scene that claimed Islamist extremists were responsible for the attack, prosecutors have since said that the man being held carried out the attack for financial gain after purchasing shares in the club, hoping to sell them after a price drop at a pre-determined figure.

"We are working on the assumption that the suspect is responsible for the attack against the team bus of Borussia Dortmund," prosecutors' spokeswoman Frauke Koehler said on Friday.

The man came to the attention of investigators because he made "suspicious options purchases" for shares in Borussia Dortmund, the only Bundesliga club listed on the stock exchange, on the same day as the 11 April attack.

He took out a loan of "several tens of thousands of euros" days before the attack and bought a large number of so-called put options, betting on a drop in Dortmund's share price, she said.

"A significant share price drop could have been expected if a player had been seriously injured or even killed as a result of the attack," according to prosecutors, though Koehler said the precise profit W. might have expected was still being calculated.

The top security official of the North Rhine-Westphalia state, Ralf Jaeger, said that the attack was fuelled by a financial motive. “The man appears to have wanted to commit murder out of greed,” said Mr Jaeger.

Frauke Koehler added that there are "no indications of possible helpers", although the investigation into whether he had any accomplices will continue.