The family of a British Airways co-pilot who believed he had been poisoned by contaminated cockpit air have accused the airline industry of having its "head in the sand" over the issue.

Richard Westgate, 43, who lived in Marlborough, died in December 2012 after moving to the Netherlands to seek help from a specialist clinic for his symptoms which he thought were caused by "aerotoxic syndrome", which has been called "pilot's disease".

Today a coroner ruled Mr Westgate died accidentally at the Bastion Hotel in Bussum, Netherlands, after taking an unintentional overdose of the sleeping tablet pentobarbital.

Prior to his death, his family said he had been in "excruciating pain" and suffering from various symptoms, including digestive problems, fatigue, general pain, headaches, loss of cognitive ability, clumsiness and inability to sense temperature.

Mr Westgate's mother, Judy, said her son's illness baffled doctors and accused the airline industry of "denying responsibility" and said they were considering legal action.

She said: "The inquest has ruled he ultimately died of an accidental overdose of a sedative - a sleeping tablet - but the real questions are: What made him so sick in the first place? And do the airline industry have something to hide?

"The results of Richard's post-mortem showed he had damage to his nervous systems and heart. The organophosphate toxins in cabin air have been shown to cause this kind of damage leading to many of the same symptoms and pain that my son experienced.

"Medical experts have said that organophosphates cannot be ruled out in causing his condition, so the questions therefore remain.

"We know there are more sick passengers and crew and we hope today will encourage the millions who fly to ask questions to ensure more is done to make sure others don't suffer like my son.

"The airlines cannot categorically say that air in these aircraft is safe. They refuse to monitor and test for toxins, so of course they have no evidence because they will not look for it.

"The longer they deny there is a problem, the harder and more costly it's going to be when they are proved wrong.

"Just like the tobacco industry in the 50s refusing to admit smoking causes cancer, the airline industry has its head in the sand.

"The inconvenient truth for the airlines is that low doses of toxins in cabin air, over hundreds of hours, can hurt people.

"The airline industry should be ashamed of itself. My son suffered so much unnecessarily and they have done nothing to protect people.

"The longer you leave it, the harder it is going to be, so we just expect those responsible to do the right thing."

She added: "One day the truth will out."

The week-long inquest in Salisbury heard that Mr Westgate had been suffering from a nervous system problem which could have caused his symptoms.

Neuropathologist Dr Daniel du Plessis said a narrowing of the arteries and lymphocytic myocarditis - an inflammation of the heart muscle - might have "quickened" his death.

But Dr du Plessis said he found evidence Mr Westgate had been suffering from neuritis - inflammation of the nerve roots - which could explain many of these symptoms, including pain, tingling sensations, numbness and balance problems.

He said organophosphate poisoning - the supposed cause of aerotoxic syndrome - could cause nerve problems but not the nerve inflammation suffered by Mr Westgate.

At the start of the inquest, coroner Dr Simon Fox QC ruled that aerotoxic syndrome would not be treated as a factor in the death.

Mr Westgate's death was initially examined by retired Dorset coroner Sheriff Payne who, in February 2015, issued a report raising concerns that more people could die unless action was taken.

He sent his Regulation 28 report to the chief executive of British Airways and the chief operating officer of the Civil Aviation Authority, as well as the Chief Coroner.

Lobby group Global Cabin Air Quality Executive is campaigning for equipment to be installed in aircraft to monitor air quality, which is supported by unions representing some airline workers.

Their research suggests that this air, known as "bleed air", can become contaminated with engine oils and hydraulic fluids, leading to illness among cabin crew through repeated exposure.

In 2015, the Unite union launched a helpline and revealed 17 personal injury claims had been made involving former and current cabin crew staff working for UK airlines.

But the industry insists that incidents of smoke or fumes on planes are rare and there is no evidence of long-term health effects.