Pirelli have released their initial findings into the tyre failures that caused heavy crashes for Aston Martin's Lance Stroll and Red Bull's Max Verstappen in Baku.
The manufacturer said the tyres in question had shown "no production or quality defect" and that the cause of the incidents had been identified as a "circumferential break on the inner sidewall, which can be related to the running conditions of the tyre".
Pirelli said that the break had occurred despite the prescribed starting perimeters for the tyres, such as minimum pressure and maximum blanket temperature, having been followed.
The analysis has now been submitted to the FIA and the F1 teams, which the regulator and Pirelli agreeing to a new set of protocols for monitoring operating conditions of the tyres during a race weekend, with an upgraded technical directive already distributed.
Stroll crashed out halfway through the race after his left rear tyre failed on the pit straight, with race leader Verstappen crashing out five laps from the chequered flag after a failure on his left rear.
A red flag period to clean up the track resulted in Mercedes uncovering a cut on Lewis Hamilton's left rear tyre, with Pirelli sending the tyres back to their headquarters in Milan for detailed analysis.
More to follow.