BRUSSELS (Reuters) -- The European Commission has written to all 28 European Union member countries urging them to widen their investigations into potential breaches of vehicle emissions rules after Volkswagen Group admitted it had understated carbon dioxide levels.
VW admitted in September it had rigged U.S. diesel emissions tests to mask the level of health-harming nitrogen oxides produced by some of its vehicles.
In a deepening scandal, the automaker said on Tuesday it had also understated the fuel consumption - and so carbon dioxide emissions - of about 800,000 vehicles.
In a letter seen by Reuters, the Commission said it was not aware of any irregularities concerning carbon dioxide values and was seeking the support of EU governments "to find out how and why this could happen."
The letter, dated Nov. 5 and signed by Industry Commissioner Elzbieta Bienkowksa and Climate and Energy Commissioner Miguel Arias Canete, asked for information by the end of this month about "any evidence or information concerning possible irregularities related to the certification of CO2 emissions values."
"If relevant, how many of the vehicles that were newly registered in your country in the calendar years 2012, 2013 and 2014 were possibly affected," the letter asked.
The Commission said it had already contacted Germany's KBA motor transport authority, which is responsible for approving the conformity of new car types, and was raising the issue with other national authorities at a meeting late on Thursday in Brussels.
A Commission spokeswoman confirmed the letter, adding it asked national governments "to widen their investigations to establish potential breaches of EU law."
"Public trust is at stake. We need all the facts on the table and rigorous enforcement of existing legislation," the spokeswoman said.
With vehicle testing in the EU overseen by national authorities, the bloc's executive body, the Commission, is reliant on each country to enforce rules.
This arrangement has come under fire from environmentalists because on-road tests have consistently shown vehicles emitting more pollutants than laboratory tests.
Car manufacturers are a powerful lobby group in the EU, as a major source of jobs and exports.
