LONDON: World champion Jenson Button cast more doubt over his future with Brawn GP on Friday when it was reported he had toured the factory of Formula One rivals McLaren.

The Guardian newspaper website said that Button and his manager Richard Goddard were shown around the factory in Woking, southern England, by McLaren boss Martin Whitmarsh.

A spokesman for McLaren told The Guardian: "Having just arrived atHeathrow Airport, Jenson made a small detour to Woking to say 'hello'."

Goddard has been talking to Brawn about a new deal for 2010 but as yet nothing has been agreed.

"As I've said many times before, Jenson wants to drive a car which is capable of winning the next world championship," added Goddard.

"We've been talking about possible terms for 2010 with Brawn for months and we're not being difficult or unreasonably expensive in our demands for Jenson. In fact we've given up quite a lot of negotiating ground in our discussions with them."

Button has been tipped to move to McLaren for the 2010 season where he would form a British 'dream team' with 2008 world champion Lewis Hamilton.