Willie Walsh, chief executive of International Airlines Group (IAG) has warned that the proposals to link Heathrow and Gatwick via a high speed rail link could be inefficient and costly.

Walsh expressed concerns about how the high speed rail link would be funded and described it the proposal as ‘sub-optimal’.

The warning followed confirmation by the Department of Transport (DOT) that a high speed rail service linking Heathrow and Gatwick is being considered by ministers to maximise capacity.

The £5 billion service, dubbed ‘Heathwick’ would enable travellers to get from Heathrow to Gatwick in just 15 minutes via 180 mph trains that would travel underground along the M25, departing every 5 minutes.

The virtual hub between airports is expected to ease capacity problems currently faced by the aviation industry.

The Government is currently reviewing its aviation policy.