Germany's Lufthansa has retaken the crown as Europe's largest airline by passenger numbers from Ryanair after the airline was forced to cut thousands of flights because of pilot rostering problems. 

The Lufthansa group as a whole carried 130 million passengers last year, it said today. 

The equivalent figure from Ryanair was 129 million, meaning Ryanair slips behind Lufthansa after overtaking it in 2016. 

Lufthansa has grown rapidly. It took over Brussels Airlines at the end of 2016 and aims to grow its budget brand Eurowings to become Europe's third largest point-to-point carrier. 

The group, which also includes Swiss and Austrian Airlines, has also benefited from the collapse of German rival Air Berlin in the latter part of 2017. Air Berlin, Germany's second largest carrier, ceased flying in October.

Ryanair, meanwhile, has curbed its growth plans after a pilot rostering issue left it without enough standby pilots to fly its planes, forcing it to cancel 20,000 flights. 

In a statement on the passenger numbers, Ryanair said: "This is expected given that Lufthansa is growing by acquisition whereas Ryanair continues to grow organically.

"Next year, as we grow to 140m passengers, we expect to overtake Lufthansa again, unless they acquire some other airline to boost their figures."

Air France-KLM reported a 5.6% rise in group passenger numbers to 98.7 million, helped by its low-cost carrier Transavia. 

IAG, the parent company of Aer Lingus, British Airways and Iberia, carried 104.8 million people in 2017, an increase of 4%. 

Lufthansa was already the largest in terms of distance, or revenue passenger kilometres, as it operates flights over both long and short distances, while Ryanair flies only short-haul routes using 737 single-aisle planes. 

Most airlines use RPK as their main measure of traffic, but Ryanair does not provide the figure in its monthly updates.