Air travel between Qatar and Saudi Arabia will resume on Monday, according to the countries' airlines, a major landmark as Doha's former rivals normalise ties under a landmark agreement.

Saudi Arabia and its allies the United Arab Emirates, Bahrain and Egypt in June 2017 slapped a blockade on Qatar that included closing airspace to the country over claims it backed Islamist groups and was too close to Iran.

Qatar always denied the charges.

The quartet agreed to lift the restrictions at a Gulf Cooperation Council summit last week in the Saudi desert city of Al-Ula, after energetic diplomacy by outgoing US President Donald Trump's administration.

The first commercial flight between Qatar and Saudi in three and a half years, a Qatar Airways service to Riyadh, will take off from Doha at 1045 GMT and touch down at 1210 GMT, according to the airline's timetable.

Saudi Airlines will fly from Riyadh to Doha, departing the kingdom at 1340 GMT according to its online schedule, with services from Jeddah expected to start at a later date.

The New York Times had reported that Qatar has been paying in excess of $100 million annually to use Iran's airspace to bypass Saudi Arabia.