The European Union's chief executive has called for a joint military headquarters and greater defence cooperation between nations as he outlined plans to combat the costly loss of Britain from the European Union.

Analysts believe Brexit could reduce the EU's military capacity by a quarter as Europe's biggest spending power departs the bloc, unless action is taken to change current defence arrangements.

European Commission President Jean-Claude Juncker said no single EU government had a military big enough to deal with security threats on Europe's doorstep as he bid to revive long-running efforts to reduce the bloc's reliance on the United States.

In his annual speech to the European Parliament, Mr Juncker said: "We must have a European headquarters and so we should work towards a common military force. This should be to complement NATO."

He added: "From an economic point of view, bringing together our military resources could be clearly justified. The lack of cooperation is something that is costing Europe 20 to 100 billion euros (£17bn-£85bn) a year."

Officials later stressed it was not a call for an EU army.