Jos Verstappen has hinted that his son Max may not stay at Red Bull beyond his 2020 contract.

Max, 21, is the clear number 1 at the team but his father Jos, a former F1 driver, suggested a move to another team cannot be ruled out.

"As it looks now, it is good for Max to stay with Red Bull. But we are watching very carefully how things go," Jos told De Telegraaf newspaper.

The comments follow rumours that the Verstappen camp has been in contact with Mercedes' Toto Wolff. Responding to those reports, Wolff admitted he is friends with Jos.

Jos said: "We thought we would have a better chance this year. But Mercedes has a better engine and a better car.

"In the current situation, it is possible that Max will not win a race this year," he added.

In late 2017, Verstappen extended his contract with Red Bull to the end of 2020.

"In the long term we have to think about what we will do in the coming years," Jos continued.

He acknowledged that the rules are changing significantly for 2021.

"Then it will be a guess as to what team you should be with," said Verstappen senior.