McLaren have rejected suggestions that Lewis Hamilton's gearbox failure in the Brazilian Grand Prix was due to him pressing the wrong button on his steering wheel.
Hamilton was seen slowing down almost to a halt on lap eight of Sunday's race, dropping from sixth to 18th place, but was then able to regain speed.
The incident sparked rumours suggesting the 22-year-old pushed the wrong button on his steering wheel, which in turn left his car in neutral until he was given instructions over the radio how to reset the system.
Compounding these rumours was a report in Montreal's newspaper La Presse, which quotes Hamilton directly as saying he indeed pushed the wrong button.
However, a source close to the Hamilton family has described the report as "absolute rubbish", telling autosport.com that Hamilton has not spoken to the Canadian newspaper or said anything as such to anyone.
A McLaren spokesperson also denied the report and said the failure was not down to human error.
"We can confirm that the temporary gear shifting problem Lewis suffered on lap eight of the Brazilian Grand Prix was due to a default in the gearbox that selected neutral for a period of time," she said.
"It was not as a result of Lewis pressing an incorrect button on his steering wheel."
McLaren F1 CEO Martin Whitmarsh also ruled out driver error and said the likely reason is hydraulic valve failure.
"It was a gearbox problem, and it went into forced-neutral and changing down seemed to rectify it - it might be mechanical, but we doubt it," he told Autosport magazine.
"If it was something mechanical, they usually don't fix themselves. It could be electronics software - but there's no evidence in the analysis to support that. Could be a sensor - but again, there's no evidence in the data recordings.
"So it would appear that the barrels that change gear went out of control - and out of control of the driver - and that's probably hydraulic.
"That could be either a very small Moog servo control valves that were interfered with by a tiny piece of debris or they are sensitive to magnetic interference - something generated a magnetic field which caused the valve to misbehave."
This week's Autosport magazine offers in-depth analysis of this issue and others in the Brazilian Grand Prix