McLaren driver Jenson Button says former teammate Lewis Hamilton could not be more wrong in his criticisms of the team and how it treats its drivers.

Hamilton, who switched to Mercedes this season, has said several times since his move that his new team gives drivers more freedom, puts fewer demands upon them for sponsorship appearances and allows them more time to themselves.

"I was very, very surprised to hear that," Button said Thursday when asked about Hamilton's comments. "The freedom I have in this team is phenomenal.

"It's so not like that. It's a very open team, free team, and a team that will do anything for you."

Button said that McLaren, unlike Mercedes, cannot use massive revenues from its road car sales to bankroll its F1 operations and therefore needs to work harder to cultivate and retain sponsors.

"In this team, you work, you have to work, and perhaps harder than in other teams," Button said. "Initially when I came to the team, it was a shock. You learn to understand, to adapt — that is the job."

As hard as McLaren may work for its sponsors, they have lost their biggest one, with the team confirming Thursday that title sponsor Vodafone will leave at the end of this season.

The team said a new major sponsor had been decided and would be announced at the end of the season.

Among the potential replacement sponsors are Honda — with speculation growing that the Japanese manufacturer will return as an F1 engine supplier next season — and Mexican communications group Telmex — which currently sponsors Sauber but may be lured to follow driver Sergio Perez to McLaren.