Charles Leclerc put Ferrari on pole position for their home Italian Formula One Grand Prix on Saturday in a qualifying session that ended in farce and with drivers under investigation.

Five times world champion Lewis Hamilton joined the 21-year-old Monegasque on the front row for Mercedes, with Finnish team mate Valtteri Bottas third and Ferrari's Sebastian Vettel fourth.

The last lap saw nine drivers cruising around, weaving and braking but with nobody willing to take the lead, and only McLaren's Carlos Sainz making it to the line in time for a final fast lap. He ended up seventh.

"That was worse than a junior formula," a fuming Toto Wolff, team principal of world champions Mercedes, told Sky Sports television.

"The problem was everyone wants a slipstream and nobody wants to go first...and then everyone looks like idiots."

Stewards summoned drivers after the session but resolved to take no further action, other than issuing reprimands and calling on the FIA to "expedite a solution to this type of situation."

Alfa Romeo's Kimi Raikkonen, the other driver through to the final phase of qualifying and last year's pole sitter for Ferrari, had earlier crashed at Parabolica -- halting the session for 11 minutes.

When the session re-started, with Leclerc on provisional pole after setting the pace before the red flag, there were minutes of inaction.

That was followed by a sudden flurry, with cars streaming out of the pitlane and jostling for position in a closely-grouped pack.

The irony of the slowest of qualifying laps at the fastest of tracks, a circuit where slipstreaming can be a huge benefit to lap times, was not lost on Hamilton, who has taken more poles than any driver in history.

"They basically timed us out," said Hamilton. "It's interesting. Get pole position in the first run and then just time everyone out.

"It's dangerous for us all. There's people slowing down and you don't know who's alongside you and that," he continued. "It's definitely risky business out there."

Ferrari's army of fans were left celebrating anyway in grandstands strewn with banners from all over Italy declaring their passion and loyalty.

The pole was Leclerc's fourth of the season and second in a row. The Monegasque will be chasing his second successive victory on Sunday after winning for the first time in Belgium last weekend.

"I'm happy with the pole but it's a shame at the end there was a big mess and I hoped our last lap was enough," said the youngster.

"I think the pace was quite good actually during the race simulations," he said of Ferrari's hopes of ending a win drought at Monza dating back to 2010, when Spaniard Fernando Alonso was triumphant.

"It's looking positive, better than in Spa."

Renault's Nico Hulkenberg, who qualified a provisional sixth and behind Australian team mate Daniel Ricciardo in fifth, took some of the heat afterwards for running off track after being first out of the pits.

He told reporters he had not done it deliberately and made a mistake after concentrating too much on what was in his car's mirrors.

"We're all looking for a tow," he said. "When you drive on your own you lose on the straights and you can't make up that time. Hence, we ended up with this situation. Of course it was a bit weird and strange.

"That's what happens when everyone starts slowing down and nobody wants to be first in the train."

Red Bull's British-born Thai driver Alex Albon qualified eighth, and blamed Hulkenberg for what had happened, while Canadian Lance Stroll will line up ninth for Racing Point.

Stroll has always gone well at Monza and qualified on the front row with Williams in 2017.

Red Bull's Max Verstappen, winner of two races this season, will start at the back of the grid due to engine penalties, along with Toro Rosso's Pierre Gasly and McLaren's teenage rookie Lando Norris.