A 32-nation conference agreed that Europe should drop its unilateral decision to impose a green tax on airlines flying into the European Union, and a majority of countries signed a declaration opposing it, a senior official said on Thursday.

All airlines using EU airports, from this year, are required to buy permits under the Emissions Trading Scheme. The scheme was introduced unilaterally, without any negotiation.

"(Charging emission fees on international aviation) is a multilateral issue, but the EU breached this principle of handling international matters," said Ji Yuan, a deputy director at the planning and development department of the Civil Aviation Administration of China.

Thirty-two countries, including China, the United States, Brazil, India, Japan, Singapore, South Africa and Argentina, participated in the international conference on cutting greenhouse gas emissions in Moscow on Tuesday and Wednesday.

"All participating countries agreed that the EU should drop its unilateral methods and return to a multilateral discussion to solve the emission issue," said Ji, who was a member of the Chinese delegation to the conference.

So far, 29 countries have signed a joint declaration opposing the European scheme.

The declaration envisages a basket of retaliatory measures to the EU emissions trading scheme, allowing any country to introduce any measure in line with national legislation to either completely scrap the ETS or to postpone it.

The measures include barring national airlines from participating in the EU's carbon scheme, lodging a formal complaint with the United Nations' International Civil Aviation Organization, ceasing talks with European carriers on new routes and imposing retaliatory levies on EU airlines.

"The conference has achieved its purpose. It will send a strong signal to the EU," Ji said.

Foreign Ministry spokesman Hong Lei on Thursday urged Europe to base its future decisions on the bigger picture of international cooperation on climate change, the sustainable development of international aviation as well as China-EU ties.

Beijing hopes the EU will beef up communication and coordination with related parties, including China, with "a constructive and practical attitude" to find an appropriate solution, Hong said.

Previously, non-EU countries expressed opposition against the scheme in various ways.

This month China's air regulator banned Chinese airlines from complying with the EU scheme. In the US, legislation is under way to ban US airlines from participating in the ETS.

Russia's Deputy Minister of Transport Valery Okulov said on Wednesday that Russia might impose restrictions on European airlines' trans-Siberia flights. A draft law to ban airlines from complying with the ETS has already been submitted to Russia's State Duma, or the lower house of parliament.

Richard Wellings of the Institute of Economic Affairs, a London-based think tank, said that the EU's policy could inflict economic damage by raising the flight cost.

"It is also deeply unfair, firstly because it unilaterally imposes the new costs on non-EU firms, and secondly because aviation is already more heavily taxed than other modes of transport," he said.

Simon Retallack, from Carbon Trust, a London-based nonprofit company, believed that the European proposal to include aviation in the ETS is "sensible" but "not ideal".

"The aviation industry, like every other sector of the economy, needs to play a part in order to help avoid the risks associated with dangerous climate change," he said.

"But if you are to ask is it the ideal solution on the global level, no. The ideal solution will be to have an international agreement on aviation emissions," he said.

At a briefing in Brussels, Isaac Valero-Ladron, EU spokesman for climate action, reiterated that the EU "will review its legislation if there is an ambitious global agreement in force because we would be covered by this agreement".

Professor Kenny Tang, CEO of Oxbridge Weather Capital, a London-based investment company focusing on environmental technology, said that the coalition of non-EU countries will give them more bargaining power.