The Dutch pilots association VNV says it is too early to hold airline KLM responsible for the fact pilots may be exposed to dangerous fumes while flying, Nos television reports.

Today, a court case will begin in the Netherlands in which a KLM pilot claims he became ill by breathing in TCP, a neuro-toxin which is found in cockpit air, Nos said. The fumes are said to come from the motor and ended up in the cockpit via the ventilation system.

Union spokesman Steven Verhagen told the broadcaster there is no scientific evidence to show breathing too many tcps can make people ill.

Nevertheless, there is growing international unease about the issue and there needs to be proper European-wide research, Verhagen said.

Television current affairs show Zembla said earlier this year that up to 35 cases of possible cockpit air poisoning where being investigated in the Netherlands.

Pilots complain of fainting and having difficulties with their vision. KLM declined to talk to the show but does have an working party looking into the issue, Zembla said.