The report, published in the journal Geophysical Research Letters, says that Western Europe's emissions of HFC-23s – an 'F' or fluorinated gas mainly used as a refrigerant – are between 60-140% higher than officially reported.
Italy alone was found to be emitting 10-20 times more HFC-23s than it officially reports. The greenhouse gas has a global warming potential which is 14,800 times higher than CO2.
The UK and the Netherlands also emitted around twice as much as they claimed, although the figures for France and Germany were "within the reported values".
"We think it is scandalous," Clare Perry, a campaigner for the Environmental Investigations Agency, told EurActiv. "These gases have a very high global warming potential over a short timeline."
There is no legal obligation on companies to reduce their HFC-23 waste gas emissions, but signatory states to the Kyoto Protocol must report their venting of the substance to the United Nations Framework Convention on Climate Change (UNFCCC).
"Nation states have to declare [HFC emissions] but their information is related to what they get from the [chemical] companies," EMPA researcher Stefan Reimann told EurActiv.
An EMPA-style evaluation of the EU's emissions inventory might strengthen Europe's hand in international talks.
"How can we expect developing countries like China and India to produce correct emissions inventories under the Kyoto Protocol when Europe can't even get it right?" Reimann asked.
The pollutant analysis by EMPA was conducted at its Jungfraujoch research station using a 'MEDUSA' special gas chromatograph mass spectrometer, which enabled more than 50 halogenated greenhouse gases to be evaluated and emission sources to be identified.
Because HFC-23s are almost exclusively emitted in the production of HFC-22s, "we exactly know our point sources," Reimann said.
EMPA pointed the finger at Italy's "sole HFC-22 plant west of Milan" (Solvay's Solexis plant at Spinetta Marengo) as being responsible for the country's over-emission of HFC-23s.
A spokesman for Belgian chemical company Solvay, Erik de Leye, told EurActiv: "We've read the publication of the Swiss and we are investigating."
He confirmed that HFC-23 waste gases were created at the Solexis plant but said the question of whether they had been vented into the atmosphere was a "difficult" one to answer.
HFC-23s are highly potent and have an atmospheric half-life of approximately 270 years, making them extremely long-lived greenhouse gases.
In January, EU Climate Action Commissioner Connie Hedegaard announced that carbon credits gained from destroying HFC-23s would no longer be tradable under the EU's Emissions Trading Scheme (ETS).
In the year 2008-2009, 84% of ETS carbon credits had been used to finance the destruction of HFC-23 plants in China and India.
Critics said that this encouraged a booming HFC-23 industry by guaranteeing a market for the substance to be bought and destroyed.
Denmark is currently calling on EU member states to ban the use of HFC-23 offsets in meeting national greenhouse gas reduction targets in the non-traded sectors.
Sixteen of the EU's 27 nations have signed the Danish proposal but others, such as Italy, have a financial stake in HFC-23 offset projects.
Perry called for the EU's ongoing review of the F-gas regulation to mandate the destruction of all HFC-23s.
"If each European country required those manufacturers to destroy HFC waste gases - and prove that they've destroyed them - it would solve the problem in a very simple and easy fit," she said.