Romain Grosjean has hit out at F1 drivers who are not members of the Grand Prix Drivers' Association.

The Haas driver has just been appointed a director of the safety-oriented body, which is also led by president Alex Wurz and fellow GPDA director Sebastian Vettel.

But Grosjean said there are too many active drivers who are not members at all.

"Formula 1 is changing, and we as drivers could achieve more if we were a unit of 20 athletes," he told Speed Week.

"I think it's ok to have different opinions, but we must unite our sport. We all want more from Liberty and we can do that better if we speak with one voice."

Asked which F1 drivers are missing, Grosjean did not hesitate to pull out his mobile phone.

"I can tell you exactly who is not with us," he said.

"Hamilton, Bottas, Verstappen, Stroll, Massa, Wehrlein, Sirotkin, Celis, Raikkonen, Hulkenberg and di Resta," said the Swiss-born Frenchman.

"When I entered F1, I wanted to be a part of it right away. So I'm a little surprised that so many are not. We're working on it."

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