Unstoppable Vettel takes pole in Monaco

The pole was the 20th of Vettel's F1 career, his fifth of the season, first in Monaco and Red Bull's sixth in six races this year.

McLaren's Jenson Button, a winner in the Mediterranean principality in 2009, will start alongside the 23-year-old German on the front row with Red Bull's Australian Mark Webber third and Ferrari's Fernando Alonso fourth.

The third and final phase of the session was red-flagged with two minutes and 26 seconds remaining when Perez smashed into the barriers at the tunnel exit, the fastest point of the street circuit.

The 21-year-old was attended to by the emergency medical team in his wrecked Sauber, while marshals shielded the scene with a large sheet.  He was then extracted and taken away in an ambulance while the shattered car, with most of its side missing and wheels dangling, was lifted and taken back to the pits on a flat bed truck.

"The most important thing was to hear that Sergio is okay," said championship leader Vettel, who has won four of the five races this year but remains without a victory on the metal-fenced circuit.

"He's conscious. We are all thinking of him and hopefully he can start the race tomorrow. "There was a bit of a shadow over qualifying when you see a colleague crash and not jumping out of the car, he added. "It is difficult to keep the focus and you don't feel 100 percent well."

The red flag came at the worst possible time for McLaren's Lewis Hamilton, the 2008 world champion, who had yet to set a timed lap in the hot and dry session.  When action did resume some 38 minutes later, after the barriers had been inspected and repaired, he was unable to do better then seventh place.

Perez's crash was almost a carbon copy of one suffered by Mercedes' Nico Rosberg in morning practice, although the German fortunately avoided the final impact with the barrier and was able to return for qualifying.  He ended up eighth on the grid, with his team-mate Michael Schumacher qualifying fifth.