Updated: More strikes planned as French air traffic walkout grounds 1,000 flights

More than 1,000 flights have been cancelled as a French air traffic control strike upends hundreds of thousands of travellers' plans. 

The industrial action - which started at 6am Friday 16 September and will run to 6am on Saturday 17 September - has forced airlines to radically slash their schedules, as other planes reroute around French airspace. 

France’s aviation authority the DGAC has warned of “severe” disruption, previously asking airlines to ground half their flights ahead of the walkout and urging passengers to delay trips.

“Flight cancellations and significant delays are to be expected,” the DGAC said in a statement.

“Passengers who can are invited to postpone their trips.”

In more bad news for passengers, the French air traffic control union has added three extra strike days.

Workers will walk off the job on Wednesday 28 September, Thursday 29 September, and Friday, 30  September.

Air France has cancelled 55 per cent of its short and medium-haul flights and 10 per cent of its long-haul flights on Friday.

Ryanair has cancelled 420 flights, affecting 80,000 passengers.

In a statement, the airline hit out at the 'unjustified' strike.

"It is inexcusable that passengers who are not even flying to or from France are disrupted," said Neal McMahon, Ryanair operations director.

McMahon called on the EU to introduce legislation to protect overflights - flights that travel through a country's airspace - from short notice cancellation.

easyJet has reportedly cancelled 'hundreds' of flights, according to French news organisation The Local. 

“Like all airlines operating to/from French airports easyJet expects some disruptions to its flying program and has been requested by the French CAA to proceed to cancellations," an Easyjet