Max Verstappen is "weak technically", according to Red Bull's former engineering boss.

Guillaume 'Rocky' Rocquelin, who currently runs Red Bull's driver development academy, says the new back-to-back world champion "still has a lot of progress to make" in that area.

"I think Sebastian (Vettel) was a more complete driver than Max when he arrived with us," he told Eurosport France's Les Fous du Volant podcast.

"At the professional level, technique, mediation, he was trained at the Schumacher school, who was his idol. I think Max maybe had more natural talent, that's what he relied on the most. But Sebastian was the most complete.

"Max has always been a boss. He has enormous self-confidence, he knows what he wants and he is very direct," Rocquelin added. "But I'll be honest - Max is weak technically compared to other drivers we've worked with.

"He is a leader by his attitude, his results. But I think he can improve from a technical point of view and in the way of developing the car."