Atletico Madrid manager Diego Simeone has admitted that the explosion incident involving Borussia Dortmund's team bus has left him worried.

Speaking ahead of his side's Champions League meeting with Leicester City, the Argentine said that he was rendered "speechless" by reports that the vehicle was rocked by a blast near to the team's hotel.

"I'm speechless. I'm concerned," he told reporters. "I have to get some more information as soon as I leave here because I hadn't heard about it, but the first thing that comes to my head is concern. Obviously."

Dortmund defender Marc Bartra was treated in hospital for minor injuries sustained during the incident, but reports suggest that he has since been released.

No other casualties have been reported.

German police have confirmed that they are treating the incident as an "attack" using "serious explosives" and are due to elaborate on their findings at a press conference later this evening.