The Telegraph reported that London's Heathrow and Gatwick, Charles de Gaulle in Paris, Zurich, Melbourne, Johannesburg, Changi in Singapore and Washington DC's Reagan Airport were among the affected.
A Heathrow spokesperson said: "A small number of airlines are now experiencing intermittent issues with their check-in systems at airports around the world - including at Heathrow".
The company operates global travel booking systems and offers check-in services for more than 130 airlines.
"Technical teams are working on the problem, services are gradually being restored", it is reported to have said. "Amadeus regrets any inconvenience caused to customers", the spokesperson said.
The problem has caused check-in delays and booking problems for many airlines including British Airways, Qantas, and Lufthansa.
New England Patriots vs Houston Texans The only time Watson didn't look like a polished product was an terrible decision early in the second quarter. The Patriots picked up Brandin Cooks this off-season after conducting a trade with the New Orleans Saints .
N.Korea mobilises aircraft in response to USA bombers Air Force B-1B bombers from Guam and F-15 fighter jets from Okinawa, Japan flew in worldwide airspace over the rogue nation. North Korea's ultimate goal, according to the minister, is reaching a strategic "balance of power with the USA ".
Ted Cruz doesn't support latest ObamaCare repeal bill
The renewed GOP drive has encountered widespread opposition from health industry groups, which have strongly opposed the effort. McCain's announcement is a near fatal blow to the legislation, which now needs every other Republican vote in the conference.
Police responding to church shooting near Nashville
Police at the scene of a church shooting at the Burnette Chapel Church of Christ in Antioch, Tennessee, September 24, 2017 . Please join me in praying for the victims of today's church shooting in Antioch, victims' families and their community.
Violent crime increases for second straight year
The largest increase in the state was aggravated assaults, a 15.5 percent increase, from about 26,600 to almost 31,000. While relatively small, those decreases came after both violent and property crime spiked in the city in 2015.
Russian general killed fighting ISIL in Syria
He added that Russian Federation wants the US' statements on combating terrorism not to be at odds with its actions on the ground. On September 16, the SDF said a Russian air strike wounded six of its fighters, but Russia denied carrying out the attack.
Lee returns as hurricane in Atlantic
It was centered about 475 miles (765 kilometers) south-southeast of Cape Hatteras, North Carolina before noon Sunday. Friday, the storm's maximum sustained winds were at 125 miles an hour, making it a still risky Category 3 hurricane.