Qatar-Saudi flights resumed on Monday as the neighbours normalise ties under a landmark agreement that ended a bitter three-year rift and allows families to reunite.

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

The first commercial flight between Qatar and Saudi Arabia in three and a half years, a Qatar Airways service to Riyadh, took off from windswept Doha airport around 11:00 GMT and touched down around 12:00 GMT.

Families hugged and laughed as they were reunited in the gleaming arrivals hall of Riyadh's King Khalid International Airport where two men waited holding large bunches of flowers which they gave to two women who arrived with a child.

"Thank God, may God save the (Saudi) King, the Crown Prince and the rulers of all the Gulf. It's a great feeling," said one tearful man on being reunited with his nephew in Riyadh.

"I am very happy! Thanks to God we have been reunited again," said his newly arrived nephew as the family kissed and embraced.

At Doha, airport staff filmed aircraft taxiing on the runway, anxious to ensure they got a clip of the relevant plane taking off, according to an AFP correspondent on the ground.

'Air bridge' 

A Saudi Airlines plane will also fly on Monday from Riyadh to Doha, departing the kingdom at 13:40 GMT according to its online schedule, with services from Jeddah expected to start at a later date.

Just as the first flight to Riyadh was preparing to take off, Qatar Airways tweeted that services to Jeddah and Dammam would resume later in the week.

Bahrain and the United Arab Emirates have both opened their airspace to Qatari aviation under the deal but there has been no word on when the first direct flights will take off to or from those two nations.

Monday’s flight flew straight across Bahrain according to specialist flight tracker FlightAware.

Saudi Arabia’s closure of its airspace forced Qatar Airways aircraft to fly over Iran, Riyadh’s arch-rival and long-time adversary of Washington, paying significant overflight fees to Tehran in the process.

The New York Times has reported that Qatar pays $100 million annually to fly over the Islamic republic, citing diplomatic sources.

The schism also complicated regional travel, divided families and raised costs faced by Qatari businesses.

US national security adviser Robert O’Brien said in November that allowing Qatari planes to fly over Saudi Arabia via an "air bridge” was a priority for the outgoing Trump administration.

The economic hit of the crisis, coinciding with low oil prices and the coronavirus downturn, was felt across the region.

Well-heeled Saudis were unable to visit Doha for holidays and long weekends while expats living in Qatar were unable to visit popular destinations like Dubai without tedious detours via Kuwait or Oman.