BARCELONA  - McLaren chief Martin Whitmarsh conceded that Lewis Hamilton could be stripped of his pole position for Sunday's Spanish Grand Prix because he was told by the team to stop on track after qualifying. Whitmarsh declined to explain precisely why the team asked Hamilton to stop, but accepted that McLaren could be penalised if it was felt they were taking advantage of an opportunity to save fuel.

That suggested that Hamilton may have been running so low on fuel that the team feared he could have failed to make it to parc ferme and have sufficient fuel remaining to supply a sample to the stewards.  Whitmarsh confirmed that McLaren were to be the subject of a stewards' meeting later on Saturday when the circumstances surrounding Hamilton's abrupt halt were to be discussed.  Talking to reporters, Whitmarsh said: "There was enough fuel to take a fuel sample, but we stopped the car -- and we are now talking to the stewards about that.

"There was 1.3 litres of fuel taken out of the car."

Asked if he was confident that Hamilton would retain his pole position, he replied: "I don't know, but I hope so. Lewis did a fantastic job throughout that session and we have all seen how difficult it is at the moment to be consistent, to switch everything on at the right time.

"Lewis and his team did a great job so it was a massive margin, by the situation within F1 at the moment, so undoubtedly he deserves to be there."

Under the rules laid down by the sport's ruling body the International Motoring Federation (FIA), drivers must return to parc ferme under their own power with a minimum of one-litre of fuel on board.

It is not acceptable for them to stop to save petrol for the sample as that would give them a competitive advantage, permitting them to run with less fuel, and hence less weight, in qualifying.

Hamilton and McLaren were given a reprimand and a $10,000 fine at the 2010 Canadian Grand Prix in similar circumstances.

At that time, the FIA Race Director Charlie Whiting explained: "Any team whose car stops on the slowing down lap after the race will be asked by the stewards to explain why this happened.

"If they are not satisfied that the reasons were beyond the control of the driver or team and feel that this has been done deliberately to gain a competitive advantage, appropriate action will be taken."

In this case, said Whitmarsh, the cause was something that happened in the McLaren garage.

"It is a technical problem that happened in the garage that didn't impede the performance of the car in any way and we stopped when it had 1.3-litres of fuel in the car.

"There was a technical problem that led to that situation. I think it is not for me to decide, but I would believe that to be a force majeure. But it is up to the stewards to decide."

He was adamant that Hamilton had enough fuel to complete his lap back to the pit lane and also to supply a one litre sample.