Saudi Arabia replaced the head of its civil aviation authority on Wednesday, after lengthy flight delays at domestic airports disrupted journeys at the start of a busy annual travel season.

A royal decree appointed Abdelhadi al-Mansouri president of the General Authority for Civil Aviation (GACA), which oversees airport operations across the country. His predecessor was sacked in January.

Local media reported cancellations and delays of up to 11 hours over the past five days as the Muslim holy month of Ramadan began, with many people making pilgrimage to Mecca and Medina or visiting family in other cities.

Disgruntled travelers took to social media to complain. A photo of an information board at Riyadh airport showed delays on almost every domestic route, and a video showed scores of people crowded outside a state-owned Saudi Arabian Airlines (Saudia) ticket office.

One passenger told Reuters that delays on Saudia had forced him to re-book on a different airline two days later. Another traveler said she saw no delays or crowding by Wednesday morning when she flew out of Riyadh with another carrier.

Saudia, which seemed to have most of the delays, called them "exceptional" and attributed them to "unusual operation conditions".

A GACA spokesman told Al Arabiya television that weather conditions and technical faults were to blame.

GACA did not immediately respond to a request for comment on the flight delays and the personnel change.