The head of Lufthansa called for a reform of workers' right to strike Friday as the biggest strike in the airline's history entered its third and final day.

While Lufthansa chief executive Christoph Franz insisted that the right to strike was a constitutional right, "from our point of view, there must be a guarantee that critical infrastructure is kept up and running.

"And that includes railways and air traffic control," Franz told the business daily Handelsblatt in an interview.

Lufthansa's pilots have been on strike since Wednesday, grounding most of the airline's flights and leaving as many as 425,000 passengers without a connection.

Lufthansa cancelled around 3,800 flights on Wednesday, Thursday and Friday as a result of the walkout by pilots who are demanding better pay and retirement conditions.

While the walkout is expected to cost Lufthansa tens of millions of euros (dollars), no travel chaos has ensued because Lufthansa was able to warn passengers in advance and help them make alternative travel arrangements.

The strike has come under heavy fire from politicians and industry, but a poll by ARD public television showed that the majority of Germans supported the pilots' industrial action.

As many as 55 percent of those surveyed said they understood the pilots' position versus 42 percent against, the poll found.

Nevertheless, the level of support is still much lower than two years ago when 75 percent of Germans said they understood a strike by cabin staff.

Lufthansa CEO Franz has said he expects services to return to normal on Saturday, even if there might be a few isolated disruptions for operational reasons.