LONDON, (Reuters) – British Airways claimed on Friday that its app and website were experiencing technical issues. There was no indication it was a hack attack. This was after complaints from passengers on social media about delayed flights and insufficient information at airports.

BA stated that it is investigating the issue and was working to fix it. It also added that their flights are still operational and customers can check in.

The National Cyber Security Centre of Britain (NCSC), a British intelligence agency that eavesdrops on the internet, warned organisations and companies to strengthen their cyber defenses after Russia’s invasion of Ukraine.

On Twitter (NYSE:), users posted messages asking BA to fix the problem. One customer posted a video showing long queues for check-in on a flight from Miami to London. Another user uploaded pictures of empty screens.

“@British_Airways, could you just update your customers?” Tessa Hartmann posted the tweet.

British Airways, which is owned by IAG, was struck by major computer problems in 2017 and left 75,000 passengers stranded for the weekend. This led to a crisis in public relations, with promises by IAG promising that things would get better.

“We’re investigating and working hard to resolve a technical issue and apologise for the inconvenience,” the airline said in a statement. “We will provide further updates as quickly as possible. “We are operating flights and checking in customers.”

Western governments issued stringent sanctions against Russian oligarchs and businesses. London ban Aeroflot from entering the UK, while Moscow banned British airlines flying into Russia.

London Heathrow Airport claimed that all systems work as usual.