A Belgian motorist has been fined for speeding in an Opel Astra at 696 kilometres per hour (432mph).

That is the speed indicated on the letter he received from police, suggesting the motorist was caught on camera travelling at half the speed of sound in Quiévrain, a small Belgian town on the French border.

The speed limit on that section of road is 50kph.

Not even the fastest Formula One car can approach such a speed, which would have meant travelling at 193 metres per second. The Astra would have been a hair’s breadth off the world record for the fastest ever wheel-driven, piston-engined car, which is just over 439mph.

In an apparent act of generosity, the computer-generated letter indicated that the motorist’s speed had been slightly rounded down - to 654.24kph.