"We had to cancel 82 individual flights," Peter Schneckenleitner told AFP. "This is more than four percent of all our flights," he added.
The cancelled service included round-trips to Calcutta, Calgary, Chicago, Dallas, Dubai and New York, Schneckenleitner said. Another 70 flights to German and European destinations were also grounded as maintenance technicians downed tools at major German airports.
The start of the strike by ground personnel Monday had seen few disruptions to Lufthansa's busy holiday schedule owing to measures taken in advance.
The service sector union Verdi has estimated its action would cost Lufthansa €5 million ($7.8 million) a day, while the airline's financial director declined to cite a specific figure. Verdi wants a 9.8 percent pay hike over a year for around 50,000 workers, while Lufthansa has offered 6.7 percent over 21 months.
The airline faces a separate movement by pilots at two subsidiaries, Eurowings and CityLine, who have staged warning strikes to press their own demands for higher wages.
In Frankfurt, around 2,000 striking Verdi members gathered before Lufthansa's headquarters on Wednesday, a union statement said.
Verdi negotiator Erhard Ott deplored "the absence of a new offer on the third day of the strike," it added.
"We should expect that it will take several days before Lufthansa comes back to the negotiating table," Verdi transport representative Gerold Schaub was quoted by the Frankfurter Runschau newspaper as saying.
A smaller union that represented cabin crews, UFO, would probably join the movement, another union figure forecast.
Meanwhile, Lufthansa said its second-quarter net profit had fallen by 21 percent to $345 million in comparison with a year-earlier figure that had included the airline's sale of a stake in the travel company Thomas Cook.
On Tuesday, the German carrier said its operating profit for all of 2008 was expected to match last year's level of €1.38 billion.
But financial director Stephan Gemkow told a telephone news conference that Lufthansa would probably not do as well in 2009.
Its bill for kerosene was tipped to hit a record €5.56 billion this year, compared with €3.86 billion in 2007, he noted.
The airline has taken measures to save €250 million in part by reducing the number of workers it hires, though Gemkow said no layoffs wereplanned for now.
He did not say how much the strike could cost Lufthansa, but added: "It's expensive, that is for sure."
In all, around 1,700 flights have been suspended to date at Lufthansa and its subsidiaries owing to labour action, Gemkow said.
He called for wage moderation, saying: "You must understand - I expect this from a union representative - that Lufthansa is involved in a very cyclical activity."