The European Union should scrap a controversial carbon tax on air travel and seek a global solution to the emissions problem, the global aviation industry's chief said on Wednesday.

The EU imposed the Emissions Trading Scheme (ETS) on January 1, but over two dozen countries, including India, Russia, China and the United States, have opposed the move, saying it violates international law.

"Nobody can deny Europe the credit for moving (environmental) sustainability up the global agenda. States are focused on the issue as never before," said Tony Tyler, director general of the International Air Transport Association.

But "the onus now is on Europe to seize the moment, take credible action to defuse the situation and get on with finding the global solution," Tyler told a business audience in New Delhi.

The EU should "forego its unilateral and extra-territorial inclusion of international aviation" in its carbon scheme, Tyler said, warning it could start a "trade war that nobody can afford".

The EU has said the scheme is designed to reduce carbon emissions blamed for climate change, and will help the 27-nation bloc achieve its goal of cutting emissions 20 percent by 2020.

But airlines have denounced the system, saying it would cost the industry 17.5 billion euros ($21.2 billion) over eight years.

India and China have been at the forefront in opposing the scheme. India in April barred its airlines from complying with the EU carbon fee, joining China in resistance.

"The rest of the world is objecting so what the Europeans fondly believe is a stepping stone to a global system is in fact a roadblock," Tyler said.

"The problem with the EU-ETS is that it is a regional, not a global scheme that everybody agrees to," said Tyler, warning the EU won't get a "global scheme unless it takes the gun away from the heads of other countries".

The EU argues the cost for airlines is manageable, estimating the scheme could prompt carriers to add between four and 24 euros to the price of a round-trip long-haul flight.

Tyler urged countries to come together to set global standards.

"We are counting on India to play an active role in these discussions," he said.