BEIJING - China opposes the European Union's "mandatory and unilateral" carbon emission tax on airlines which Chinese experts called "a green barrier".

Europe's highest court upheld on Wednesday the right of the EU to impose a carbon cap-and-trade scheme on international airlines using European airports.

Many countries have come out against the EU move.

China hopes that the EU will act with caution and settle the issue in a positive and pragmatic way through consultation with relevant countries, Ministry of Foreign Affairs spokesman Liu Weimin said on Thursday.

According to the plan, all airlines flying to and from the 27 EU countries will have to pay for 15 percent of the polluting rights accorded to them in 2012, which will rise to 18 percent from 2013-2020.

The European Court of Justice ruled on Wednesday against a group of US airlines that challenged a European law requiring a carbon cap on all airlines flying to and from EU airports and forcing them to purchase permits from Jan 1 under the EU's emission trading plan.

Chinese airlines are also planning to follow the US step and file a suit against the EU.

"Air China is strongly against the carbon emission trading scheme and is looking for proper ways to solve the issue," Rao Xinyu, board secretary of Air China, said.

The scheme will have consequences for domestic airlines which are eyeing expanding their operations to and from Europe, said Lu Lingfei, deputy general manager of Air China's strategy and development department.

Lu said the EU will grant airlines a certain quota for free carbon emissions based on the records of their flights to and from Europe.

"Based on existing records, the total free emission quota for four Chinese airlines that have routes to Europe will be no more than that for a single established European airline," he said.