A 25-hour strike by ground handling staff at Berlin’s airports caused chaos at travel trade show ITB in Berlin on Friday.

The departing flights of most trade visitors to the world’s largest international travel fair were cancelled after trade union Verdi called the strike at a day’s notice.

The action over a pay claim was expected to halt almost all flights at Berlin airports Tegel and Schoenefeld on Friday as many of the 120,000 trade visitors to ITB sought to leave.

Departing flights on Saturday were booked out within a short time of the strike notice, leaving many stranded over the weekend.

The Berlin airports authority warned of delays and cancellations over the weekend owing to air traffic control restrictions.

Service union Verdi is demanding a pay increase of €1 an hour or about 9% for the next 12 months. The airport employers have offered an 8% rise spread over three years and refused to negotiate.

Ground handlers voted by almost 99% to strike in a ballot announced last week and have staged a series of warning strikes at other German airports before announcing they would focus their action on ITB.

The strike hit flights by carriers including easyJet, Ryanair, British Airways, Lufthansa/Eurowings and Air Berlin.

A Ryanair spokesman apologised to customers for the “unwarranted union strike” and said passengers had been offered either a full refund, a free transfer to the next available flight or a free transfer onto an alternative flight route.

“We regret that we have been forced to cancel a number of flights to/from Berlin today (10 Mar),” he said. “All affected customers were contacted by email and SMS text message and advised of their options.”