Lewis Hamilton says the slow speeds Formula 1 drivers needed to run at to prepare for their Belgian Grand Prix Q3 qualifying laps left them in a "dangerous" situation.
A number of cars bunched up ahead of the first runs in Q3, as drivers were eager to stay close to those in front of them so they could benefit from a tow, and keep their tyres in the right operating window.
Hamilton nearly ran into the back of team-mate Valtteri Bottas at one point as they slowed to avoid faster cars approaching them, while Bottas later locked up to avoid hitting Nico Hulkenberg.
"I think this year is definitely the slowest we have been, and today felt a little bit dangerous at one point because we were going around Turn 15 on the kerb and there was a car coming and I couldn't move," said Hamilton.
"I couldn't go on the grass. I was stuck behind Valtteri and Hulkenberg.
"I can imagine that if I was on a lap and I was coming around to find everyone crawling around at 5mph it would be a bit of a worry and a bit of a distraction.
"I am not really sure what we can do to stop it from happening. Maybe we have to be on the pitlane speed limiter or something like that.
"You should not be able to go at 5mph or 2mph or whatever... it was literally going as slow as possible to let people past.
"I did it in Austria I think to let everyone by because I was the first guy out there and the tow is so strong this year with these cars.
"They talk about the front wing being easy to follow but it has just caused a lot more drag, it is a draggier car this year so the tow is a lot more powerful than we have ever experienced."
Ferrari's Sebastian Vettel believed the situation was exacerbated because tyre temperatures are now critical to performance.
Asked if he felt new rules were needed to prevent this type of situation, Vettel said: "I am not in favour of any more rules, I think we have too many anyway.
"What we should change actually, and what we should take from this seriously is that tyre-wise, we should not be so much on the limit.
"Obviously you are fighting for a tow and so on, but you are also fighting to get into the optimum window which years ago it was not that critical whereas now it is.
"You are fighting for the best spot on the track, which will hit the peak in Monza for finding the right tow because it does make the difference, but that has always been part of those type of tracks.
"But I feel if we had better tyres, we could play with probably a bit more speed and so on."