An extra 28 million passengers a year could take to the skies if European airports were allocated slots more efficiently, a study by the European Union has concluded.

The study into the use of Europe’s airspace and major hubs found that more efficient use could add £4.4 billion to the economies of Europe between 2012 and 2015.

It highlights the problem of capacity worsening in many busy airports, such as London Heathrow and Paris Orly, due to their failure to expand.

The research studied the way airport slots are allocated to airlines, and recommends secondary trading of airport slots across the EU, based on what it says is successful experience at London airports.

The study could lead to the European Commission approving new legislation aimed at tackling congestion.

The UK market remains Europe’s largest, handling 214 million air passengers in 2010, the aviation website anna.aero reports. This was followed by Spain (193 million passengers), Germany (191 million), France (143 million) and Italy (140 million)

The European Commission plans to introduce legislation within months to address the problem of airport congestion in Europe.