Richard Hammond was driving a jet-powered dragster

The "catastrophic disintegration" of the jet car's front tyre was probably caused by an object like a nail, a BBC report has concluded.

The 88-page document criticised the Top Gear team for not having anyone present "with sufficient knowledge to assess the adequacy" of the safety checks.

Hammond crashed while driving at speeds up to 288mph at an airfield near York.

According to the report, the underlying cause of the incident was "the inability to spot the damage to the tyre".

Safety checks on the day were made by PrimeTime Land Speed Engineering (PLE), the company that provided the Vampire jet car Hammond was driving, the BBC said.

Hammond suffered brain injuries and was airlifted to hospital

But the evidence was "inconclusive whether the safety checks, especially tyre checks, were being conducted to an appropriate standard", the report decided.

The report concluded that, where experts were given "prime responsibility" over safety, the BBC must ensure it selected "competent persons".

The Health and Safety Executive published its report on the crash in June.

It spotted failings in "risk assessment and the procurement of services from others" but also identified precautions that "almost certainly saved Mr Hammond's life".

After that report was published, PLE issued a statement saying its cars were "designed, built, maintained and constantly updated to embrace or exceed all current standards".

'Safety first'

"The team's reputation for putting safety first is well known in drag racing, airshow and speed record breaking circles," it said.

The Vampire's tyres, it added, had been bought new not long before the crash.

The Top Gear team were praised elsewhere in the BBC report for areas of good practice.

These included a decision by executive producer Andy Wilman to drop initial plans to attempt a land speed record.

It also said emergency services were at the scene of the crash "within seconds".

And it recommended a series of measures to improve risk management in programmes involving "high risk activities".

Hammond crashed on 20 September at Elvington Airfield while making his seventh run of the day in the jet-powered dragster.