The Army's £6.3billion Ajax armoured vehicle could be poisoning troops with toxic carbon monoxide fumes, a damning safety report has revealed.

The official report, obtained exclusively by the Mail on Sunday, has sent shockwaves through the Ministry of Defence, with fears the beleaguered vehicle requires millions of pounds more of public funding to solve a litany of problems.

The MoS can reveal that a team of army safety inspectors have concluded there is no single cause for a crisis sparked last year when more than 30 soldiers operating the fighting vehicle fell ill during a military exercise on Salisbury Plain

Instead, Ajax is beset by a 'mutli-factor combination' of problems, including 'faulty headsets', mechanical defects and possible missing air filters and leaks that could be resulting in the accumulation of carbon monoxide and carbon dioxide fumes inside the vehicle.

The Army is due to receive 589 Ajax vehicles, which are to form the backbone of its armoured strike brigades for the next 30 years. The first 40-ton vehicles should have entered service in 2017 but they have been plagued by problems, prompting former defence secretary Ben Wallace to call it 'a ridiculous project'.

Early trials were suspended after troops suffered hearing damage, with 310 soldiers needing to have assessments after riding in the vehicles. The programme was plunged further into crisis last November when 33 soldiers operating 23 different vehicles began suffering symptoms including nausea, vomiting, numbness, hearing loss, muscle pain and pins and needles during an exercise called Titan Storm.

Now leaked details from the Army's official safety investigation into the incident reveals an alarming array of issues, including the possible exposure of soldiers to toxic gases.

Inspectors identified problems with the vehicles' tracks, loose or missing 'engine deck bolts' and unreliable power units, which are meant to provide electrical power when the main engine is off. 'Their combined effect is assessed as capable of increasing exposure to noise, vibration, heat, fumes and workload,' they said.

They also discovered that 'faulty communication headsets and configuration errors' were 'likely contributors to noise injury symptoms'.

Meanwhile, 'possible missing filters, leaks and incorrect hatch states' may have caused conditions in which soldiers could be exposed to carbon monoxide and carbon dioxide fumes. The soldiers' symptoms were 'consistent' with such exposure.

Colonel Hamish de Bretton-Gordon, a former tank regiment commander, said: 'If they have identified that filters are faulty or missing, that is a serious problem. But actually it's a very easy problem to fix - you just put new filters in them.'

The inspectors found that when maintained and operated properly, Ajax is not unsafe but they also warned 'the interaction of multiple factors may create conditions in which personnel experience symptoms of ill health.'

Their damning report added: 'The evidence to date indicates no single causal mechanism. Instead, it points to a multi-factor combination involving platform condition, environmental stressors, system reliability, user behaviour under operational pressure, training and experience variability, cold exposure, and possible fume or CO/CO2 [carbon monoxide/carbon dioxide] exposure.'

The MoD was due to update MPs on the project last Thursday - but the announcement was delayed until early this week. Sources do not expect Ajax to be completely axed but the safety report raises the prospect of the cash-strapped MoD having to find millions more funding to fix it.

Col de Bretton-Gordon added: 'The safety report has identified a whole host of issues. These issues are all fixable - and the MoD can only go forward with this if it funds them.'

The MOD said: 'The safety of our people is non-negotiable. An extensive safety investigation into Exercise Titan Storm has now concluded, with an update to Parliament expected in the coming days.'