Saudia Airlines has been fined some €1.4 million by a regional Belgian government for breaching EU carbon emissions rules, making it the first big non-EU carrier to be fined for breaking the EU aviation law.
The European Union requirement that all aircraft using its airports pay for carbon emissions caused international outcry when it was introduced at the start of 2012.
Among the staunchest opponents was Saudi Arabia, which told its state-run airline not to comply. India and Russia were also outspoken critics.
Faced with threats of a trade war, the EU changed its legislation to apply only to flights within the bloc, rather than the entire length of flights in and out of EU airports. That still included EU flights carried out by non-EU operators.
While European airlines have largely complied, some non-EU airlines have not and environment campaigners say EU governments have been slow to collect fines.
Belgium, however, has exacted a fine on the Saudi airline which ranks as the biggest yet, officials said.
In a written parliamentary answer seen by Reuters, the Flemish Environment Minister said that two operators were fined €100 for every EU Emissions Trading System they failed to submit, the other being smaller US operator Green Diesel which incurred a fine of €6,600. However, the company ceased operations from 2013 and the fine cannot be collected.
The fine on Saudia applies to all its intra-EU flights, since airline operators report to one authority only.
Officials in the aviation industry in Saudi Arabia declined to comment. The European Commission was not available for comment.
The German Emissions Trading Authority (DEHSt) earlier this year published a list of 44 non-compliant operators it fined for not surrendering carbon allowances in 2012, including Air Berlin and Air Arabia Egypt.
Britain's Environment Agency also fined five airlines for non-compliance in 2012, including Air India.
However the EU Commission said on Monday compliance was high, with operators accounting for 99% of aviation emissions complying with the rules.
At talks in Paris later this year to try to agree a new UN deal on tackling climate change, Saudi Arabia, one of the world's biggest oil producers, is expected to resist calls to limit use of fossil fuels.