Sebastian Vettel admits there was no obvious indication of what caused his high-speed crash during testing in Barcelona on Wednesday.

The German slammed into the barrier as he entered Turn 3 midway through the morning, causing a 40-minute red flag period to recover his stricken car.

Ferrari only confirmed that a mechanical issue had occurred and when back in the paddock, Vettel was unable to elaborate further.

We don't know much more than everyone knows," he told reporters and was quoted by GPFans.com.

"Inside the car, I was going into Turn 3 and then, by the feeling, there was an issue with the front left corner and from there, there wasn't anything I could have done to avoid the impact.

"I wasn't in control anymore and went more or less straight into the barriers."

His comments do at least confirm the reports from trackside that the left-hand side of the front wing was sparking along the track moments before the accident, perhaps indicating a tyre failure or suspension issue though that is just speculative.

Ferrari has confirmed a prolonged delay to repair the SF90 but of greater importance is to discover whether any kind of inherent problem was to blame.

"We are flat out trying to understand, obviously it would be a lot easier if there was a lot of run-off and the car didn't hit anything because now, you can imagine, obviously it's fairly damaged due to the hit," Vettel continued.

"So we have to be careful understanding what exactly is the problem and that's what everybody is looking at here at the track and at Maranello. It's important to us."