Police now believe the motivation for the incident may have been financial, with prosecutors claiming the suspect - identified as Sergej W - had carried out the attack for financial gain.

Prosecutors say the suspect, who has been charged with attempted murder, causing an explosion and serious bodily harm, had considered the impact of the bombings on the Bundesliga clib's share price.

They said he bought a significant number of put options for shares in Dortmund, which would have allowed him to sell them at a pre-determined even if they fell in value in the wake of the attack.

"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," prosecutors said.

Three devices, containing pieces of metal, were detonated near to the bus carrying the Dortmund team to their stadium, Signal Iduna Park, for the Champions League quarter-final first-leg against AS Monaco on April 11.

Police originally suspected an "Islamist motive" after they found two letters at the scene, each claiming responsibility.

Prosecutors revealed last week that they were investigating a third claim of responsibility for the explosions, with the Tagesspiegel newspaper reporting they had been sent a letter apparently written by far-right groups in the country.

One of the letters reportedly referred to the terrorist attack on the Berlin Christmas Market in December and military operations in Syria.

Lead prosecutor Koehle said authorities had "considerable doubt" over the credibility of the letters, with another giving a left-wing extremist motive for the incident.

They dismissed the "Islamist" link when they cleared their original detainee of involvement in the attack, which left Spanish defender Marc Bartra requiring surgery on a fractured wrist.

The 26-year-old, who had been due to start the Monaco match, was released from hospital on Saturday (April 15).

Dortmund manager Thomas Tuchel had criticised UEFA for rescheduling the first leg, which the German side lost 3-2, for 24 hours after the incident.

Tuchel claimed European football's governing body made them feel "impotent" and that the club were "completely ignored" in UEFA's decision making process.

In response, UEFA insisted the decision was made in "complete agreement with clubs and authorities".

The 43-year-old, Dortmund manager since 2015, said today that it was "a good sign" that a breakthrough had been made in the case.

"It's important for our players and staff that the case is solved quickly," he added.