Fernando Alonso was "conscious" as he was airlifted to hospital on Sunday after a crash on the final day of the Barcelona test.
The Spaniard was initially taken to the circuit medical centre by ambulance, after his McLaren hit the unprotected concrete wall at turn four.
The Circuit de Catalunya said Alonso is "ok and conscious"; a brief message reiterated by his manager, Luis Garcia Abad.
"It seems that he is ok," circuit officials added, explaining that the trip to hospital is to "continue with medical tests".
After a delay, McLaren said only that the 33-year-old is "conscious" and "speaking".
Auto Motor und Sport said Sebastian Vettel was following Alonso at the time of the crash.
"The speed was slow - maybe 150kph. Then he turned right into the wall. It looked strange," said the German.
It is understood that a car carrying members of the Ferrari team, for whom Alonso raced between 2010 and last year, left the track to check on its former driver.
Earlier, new Ferrari chief Maurizio Arrivabene said the fabled Italian marque does not blame Alonso for the chaos of 2014.
"It was the overall situation," he insisted. "When people are under pressure they are going to be divided. Accusing Fernando is not my intention.
"I have a lot of respect for Fernando. We have a good relationship," he added.