The services union Ver.di warned on Wednesday that ground and board personnel for German flagship air carrier Lufthansa would conduct warning strikes on Thursday morning. The union, which represents more than 52,000 of the international airline's employees, said a strike would begin at the Frankfurt Airport Thursday morning at 5:30 a.m. and continue for three hours.

The union said as many as 1,000 board, ground, catering and shipping services personnel would partake in the warning strike, which follows a collapse in negotiations between the union and Lufthansa executives on Tuesday.

Ver.di began negotiations demanding a 9 percent wage increase for employees. Lufthansa has made a counteroffer of an immediate 2.4 percent raise and an additional 1.5 percent at the end of the year. The company has also offered a results-based annual payout that is the equivalent of 1.6 percent of a person's average yearly income.