The European Commission has warned Britain not to attempt an "open skies" agreement with the US ahead of a ruling in the high court to decide if such a move is legal.

The EU wants to agree a deal with America over access to US airports, but wants to secure an agreement for all 15 members of the European Union together rather than on an individual country basis.

However, Britain and the US have been looking at ways to extend an already existing aviation agreement to loosen restrictions on trans-Atlantic flights.

The European transport commissioner has written to the British government to complain that a separate deal with the US could hamper a deal with other European airlines.

Playing fair

The European Court of Justice is already investigating a case against eight members of the EU who have made their own aviation agreements with America.

The transport commissioner Loyola de Palacio has told the UK foreign secretary Jack Straw that she is concerned about the investigation.

A spokesman for Ms de Palacio said this was "because if the court declares such agreements illegal, that would pose a major problem".

The EU is seeking a Europe-wide agreement over which routes can fly into the United States.

It said separate agreements would "undermine efforts at the EU level, and it would make negotiations with the US more difficult".

Changing flight path

Under the current agreement, US airlines can fly into European countries from anywhere within the United States.

However, European airlines can only fly into the US from their own home countries.

The commission suggests that a group negotiation is needed for European airlines and that the present rules make it difficult for European carriers to merge.

With a number of European airlines currently struggling to make profits, the EU argues that consolidation, as has taken place in the US, could be a solution.