Sebastian Vettel will start today's Abu Dhabi Grand Prix from the back of the grid due to a fuel irregularity.

After setting the third-fastest lap in qualifying, behind pole-sitter Lewis Hamilton and Red Bull team-mate Mark Webber, the drivers' championship leader was ordered to stop his car on his in-lap at the Yas Marina Circuit.

Following a lengthy stewards' investigation, Vettel's demotion was declared four hours and 40 minutes after the qualifying session had concluded.

The 25-year-old German now faces a battle just to get into the points, leaving title rival Fernando Alonso with a great chance to close the 13-point gap between them.

A statement from the FIA read: "The stewards received a report from the race director [Charlie Whiting] that car one [Vettel] 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 driver and team representatives and studied telemetry evidence that showed the reason why the car was stopped. The stewards accepted the explanation and considered the incident as being a case of force majeure.

"However, a report was received from the technical delegate that showed during post-qualifying scrutineering an insufficient quantity of fuel for sampling purposes. The stewards determine this is a breach of article 6.6.2 of the FIA Formula One technical regulations and the competitor is accordingly excluded from the results of the qualifying session. He is, however, allowed to start the race from the back of the grid."

The incident is virtually identical to the one involving Hamilton following qualifying for the Spanish Grand Prix in Barcelona in May. This time around, the Englishman proved to be untouchable as he claimed his sixth pole this year and 25th of his Formula One career.

The 27-year-old was fastest throughout all three sessions around the Yas Marina circuit that was bathed in warm fading sunshine when the session began and was under the floodlights when it ended.

Hamilton finished a third of a second quicker than Mark Webber, while Williams driver Pastor Maldonado moved up to third in the grid after Vettel's demotion, ahead of Kimi Raikkonen in his Lotus and Jenson Button of McLaren.

Ferrari's Alonso, who trails Vettel after leading the championship until recently, will begin the race in sixth.

After the middle 15-minute session, neither Force India made it into Q3 for the second straight race, as Nico Hulkenberg qual-ified 10th and Paul di Resta 12th.

A fading Michael Schumacher, heading into retirement for a second time at the end of the year, starts 13th in his Mercedes.

As for Hamilton, he was unable to explain where his speed had come from, even though this has long been one of his better tracks. "I don't know," Hamilton responded when asked. "The car has been feeling fantastic, great from the get-go, but we've no upgrade package so I don't know. It was just great."