Lewis Hamilton has been dramatically moved to the back of the grid for today's Spanish Grand Prix after being excluded from yesterday's qualifying session.

McLaren were found guilty of a fuel irregularity under the current FIA technical regulations as Hamilton stopped on track after seemingly claiming the team's 150th pole in Formula One.

McLaren had cited force majeure and had hoped to remain on pole, but following a lengthy stewards' hearing last night, the 27-year-old and his team have been handed a severe penalty.

An FIA statement read: "The stewards received a report from the race director (Charlie Whiting) which stated that during post-qualifying scrutineering a sample of fuel was required from car 4 (Hamilton).

"However, the car failed to return to the pits under its own power as required under article 6.6.2 of the FIA Formula One technical regulations.

"The stewards heard from the team representative, Mr Sam Michael, who stated that the car stopped on the circuit for reasons of force majeure.

"A team member had put an insufficient quantity of fuel into the car, thereby resulting in the car having to be stopped on the circuit in order to be able to provide the required amount for sampling purposes.

"As the amount of fuel put into the car is under the complete control of the competitor, the stewards cannot accept this as a case of force majeure.

"The stewards determine that this is a breach of article 6.2 of the FIA Formula One Technical Regulations and the competitor is accordingly excluded from the results of the qualifying session.

"The competitor is, however, allowed to start the race from the back of the grid."

The man who will now sit on pole will be Pastor Maldonado in his Williams after the Venezuelan's produced the best qualifying performance of his F1 career.

Home town hero Fernando Alonso will be second, but Red Bull's double world champion and series leader Sebastian Vettel qualified eighth – but will now start seventh – without setting a lap time in the final session.

Vettel's Australian team-mate, Mark Webber, saw his hopes of a third Spanish pole in a row disappear when he failed to make the cut for the final session and qualified 11th.

That was one place behind Hamilton's British team-mate and 2009 champion Jenson Button, who will also be able to change his car's set-up with tyres saved for the race.

"I don't know where it went wrong. All day I've struggled with balance," said Button, who had been fastest in Friday practice.

Maldonado produced a stunning performance in qualifying, going quickest in Q2 before being beaten by a sterling Hamilton at the end.He said: "We've made a good step forward for this race and now we need to keep pushing."

In front of his home fans, and after previously qualifying no higher than eighth this season, Alonso was naturally delighted to break into the top three in a car whose upgrades are clearly working for him at least, unlike team-mate Felipe Massa.

"It was impossible to even dream of being in the top three in the first four races," said Alonso.

"We've improved a few tenths of a second and that means a big step forward in position. Hopefully we can capitalise on this good starting position."

The Lotus duo of Romain Gros-jean and Kimi Raikkonen start third and fourth with Sergio Perez sixth for Sauber. Nico Rosberg is seventh for Mercedes, with team-mate Michael Schumacher eighth.

Force India's Scottish driver Paul di Resta and Nico Hulkenberg start 12th and 13th.