Melbourne, Feb 16 : Some of the most popular airlines in the world have high levels of "toxic" fumes on their aircrafts, which could prove dangerous to both passengers and crew, according to a probe.

German television network ARD, along with Swiss broadcasters Schweizer Fernsehen, took swab samples and found levels of a dangerous toxin onboard several planes.

Leading toxicologist Professor Christian van Netten analysed 30 swabs in total, which were taken by undercover journalists, and found that twenty-eight samples contained high levels of tricresyl phosphate (TCP).

Found in modern jet oil, TCP can lead to drowsiness, headaches, respiratory problems or neurological illnesses-a condition scientifically know as Aerotoxic Syndrome.

The researchers said that because the air in aircraft cabins is usually not filtered, TCP could easily seep in via air conditioning and inhaled by cabin crew and passengers.

Swedish pilot Neils Gomer revealed in February last year that he was almost completely incapacitated by toxic fumes, which also left passengers in a "zombie-like condition".

According to The Telegraph, the incidents of contaminated air on aircraft are referred to in hundreds of reports filed by pilots in recent years.

Last year, Australia's Civil Aviation Safety Authority set up an independent team to investigate the possibility of dangerous toxins on passenger planes.

And the Expert Panel on Aircraft Air Quality (EPAAQ) includes medical doctors and a professor of toxicology and the University of New South Wales.

"Following the ongoing debate on whether cabin air quality is an issue, we have set up a 10-man team of experts to look at all the research that has been done; any information from Australia and to review all the evidence," News. com. au quoted CASA spokesman Peter Gibson as saying.

He said that though many people made claims, no definitive scientific evidence had been found to prove aircraft poisoning to date.

Gibson said: "While we haven't heard of people getting sick regularly when they get off aircraft, we do take the claims seriously and want to know about it. The evidence is simply not there at this stage that aeroplanes are making people sick."

He is hoping that the results from the investigation would be released in 2010. (ANI)