McLaren understands Jenson Button's concerns over F1 future

Both Button and Kevin Magnussen are waiting for McLaren to confirm its driver line-up for 2015, amid rumours that Fernando Alonso could be returning to the team from Ferrari.

When asked during a media phone-in on Tuesday if he was concerned that Button was unhappy with the uncertainty, Boullier said: "No.

"Obviously I understand that he may not feel comfortable and he is concerned about his future.

"But, again, I am in charge of McLaren Racing and we have to build the best for our team, and drivers are very important in our discussions.

"Jenson is more than considered to stay with us for long-term, but we are still investigating what we want to do with our driver line-up once we have all the data in our hands."

Boullier dismissed suggestions that Button needs to prove himself to McLaren in the final races of the 2014 season, and he said the team still hopes to announce its decision before the end of the campaign.

"We know the value of Jenson," he added. "He is a world champion, and a world champion-class driver.

"We don't need him to deliver next time on track to - let's say - save his job.

"I hope to sort out our decision on the driver line-up before the end of the season.

"It's true that it's taken a bit more time, but it's still on course to be announced before the end of the season, yes."