'Undetectable problem' caused loose Baku manhole cover

Officials from the Baku City Circuit confirm the cause of the loose manhole cover that ultimately led to the cancellation of opening F1 practice on Friday.

Officials from the Baku City Circuit have confirmed that an "undetectable problem" was to blame for causing a manhole cover to come loose during opening practice for the Azerbaijan Grand Prix on Friday, ultimately leading to the session's cancellation.

George Russell ran over the loose manhole cover on the run to Turn 3 early in FP1 on Friday, cracking the chassis of his Williams FW42 car in an incident that has ruled the Briton out of running until Saturday morning.

FP1 was then abandoned due to the incident so that organisers could complete safety checks, with more than 300 manhole covers to review around the 6km circuit.

The Baku City Circuit issued a short statement on Twitter on Friday afternoon confirming the checks had been completed, as well as explaining the cause of the issue.

"FP1 was unfortunately cancelled due to a loose manhole cover. Although all safety and regulatory checks had been put in place beforehand, the resulting issue was caused due an undetectable problem beneath the fitting that only became apparent this afternoon," the circuit said.

"We have coordinated with FIA to secure a replacement cover and to check all other manholes on the circuit before racing can resume. Driver safety is always paramount and our main priority. With over 300 manholes on the circuit, this process will take some time."

Track action in Baku resumed with Formula 2 qualifying, which was delayed by 30 minutes to 12:30pm BST.

Second F1 practice is set to take place at 2pm BST.