In Greece, air traffic controllers have threatened to join a 24-hour walkout by public sector employees on Wednesday (9 April). The same day, easyJet flight attendants in Italy will strike for four hours from 10.30am to 2.30pm local time.

The Greek Air Traffic Controllers Association said only a limited number of non-commercial flights would be able to operate during the strike period, including medical, search and rescue, humanitarian, military and emergency services.

It follows a strike in February, which grounded flights, although the impact of a spring walkout would likely be more widespread as travel’s summer season gets under way.

Greek carriers Aegean and Olympic Air has warned travellers due to fly on Wednesday of the possibility of strike action and is offering them free flight changes or the option to cancel in return for a voucher.

"The participation of the air traffic controllers in the strike may be suspended following a decision by relevant court of law," said Aegean. "Until then, and while waiting for the relevant decision, there will be no changes on the Aegean and Olympic Air flight schedules."

According to reports in the Greek press, public sector union Adedy is seeking reinstatement of annual holiday bonuses for public sector workers.

Meanwhile, Wednesday’s strike in Italy is being led by trio of labour and transport unions. An easyJet spokesperson confirmed to The Independent the airline had been formally advised of a hour-hour strike involving "some Italian-based cabin crew unions" which they said was expected to impact some flights to and from airports in Milan and Naples.

Customers whose flights are impacted will be contacted directly.