Pirelli has reported an above average number of cuts from debris in its Formula 1 tyres for a second grand prix in a row in Italy.
Tyres have been under the spotlight after failures at high speed for Ferrari's Sebastian Vettel and Mercedes' Nico Rosberg at the previous F1 race in Belgium.
Following an extensive investigation, Pirelli found 63 cuts in the tread of the tyres used over the course of the Spa weekend.
That compares to an average of 1.2 cuts per circuit in the previous 15 events, which includes races and tests, and Pirelli motorsport director Paul Hembery said there had been further concerns at Monza.
"We got a large piece of glass out of one tyre, which is of course not what you expect to see," he told AUTOSPORT.
"Over the weekend, we have seen a reduction in the number of cuts as the tracks cleared.
"But there were quite a number of incidents on Saturday and we saw the debris picked up in the tyres."
Asked how the number of cuts related to the 1.2 average Pirelli had quoted, Hembery said: "It's higher than that."
A large amount of debris was scattered across the track when Max Verstappen's Toro Rosso dramatically shed its engine cover during qualifying, after the team failed to secure it properly.
Hembery reiterated Pirelli's call for changes to the way F1 circuits are cleaned during grand prix weekends.
"You have to ask, where did a piece of glass come from? It was quite substantial," he said.
"Maybe some could say we're maybe more sensitive to these situations which is probably true in many respects.
"But also true we're seeing situations that are not what we have seen over the last five years.
"We need to find a standardised way of cleaning circuits. I know it's something the FIA are looking at."