Saudia Group signed a deal with Lilium on Thursday to purchase 100 all-electric flying shuttles, the Germany-based air taxi developer said, one of the company's biggest orders yet as it works to develop the aircraft.

The Saudi state-owned airline made a firm order for 50 of Lilium's electric Vertical Take-Off and Landing (eVTOL) Jets with an option for an additional 50 later, Lilium said.

The first aircraft are expected to join the Saudi state-owned airline's fleet in 2026.

The deal-signing took place at Lilium's headquarters outside Munich during a trip by Saudia executives to Germany.

The value of the deal was not given.

Delays in the delivery of testing equipment and other parts have forced Lilium to push back the first manned flight of its vertical take-off aircraft until the beginning of next year, it said on Wednesday.

Lilium is competing in a crowded market for eVTOL vehicles, hoping to replace road trips or short hops by aircraft or helicopters.

According to Saudia, it will use the air shuttles to transport pilgrims between Mecca and Jeddah, and to transport guests to major sporting events in the capital Riyadh as well as tourist destinations.

(Reporting by Alexander Huebner in Munich, Writing by Rachel More, Editing by Madeline Chambers)