McLaren junior Alex Dunne and Alpine reserve Victor Martins clumsily tripped over each other at Sainte Devote, setting off a multi-car pile-up.

Martins appeared to squeeze Dunne into the first turn, causing the pair to make wheel-to-wheel contact.

Just a handful of cars made it through the mess with less than half the field making it back to the grid when the red flag was drawn.

“Huge incident in the Formula 2 feature race here,” said commentator Chris McCarthy.

“It has taken a load of drivers out there. Our championship leader Alex Dunne out of the race, red flag out.”

The race was delayed for more than half an hour before resuming behind the Safety Car with 15 of the 22 cars remaining in the race.

Joining Dunne and Martins in retiring were Richard Verschoor, Gabriele Mini, Ritomo Miyata, Pepe Marti, and Max Esterson.

Leonardo Fornaroli led the field to green in what was shortened to a 30-minute contest.