BERLIN: Borussia Dortmund chief executive Hans-Joachim Watzke considered withdrawing the club from the Champions League following Tuesday's attack on its team bus.

Watzke tells Der Spiegel magazine, "I briefly considered whether we should pull out of the competition completely. But then it would have been a victory for the perpetrators."

He says the attack wasn't just an attack on Dortmund "but rather an attack on the Federal Republic of Germany."

Defender Marc Bartra and a police officer were wounded when three explosions hit the team bus as it was leaving for the stadium ahead of the first leg of the Champions League quarterfinal against Monaco.

Investigators are examining a number of claims of responsibility, the latest containing far-right rhetoric. Links to Islamic extremism and left-wing radicals are also being probed.