Facebook has been accused of disabling a large number of user accounts in Hungary.
One user, David Butykai, told BBC News his Facebook and Instagram accounts had been blocked and between 30 and 40 of his friends in the country had experienced the same issue.
A number of Hungarian media outlets have also said that affected users have contacted them.
The BBC has contacted Facebook for comment.
"I have stored a lot of important data on Facebook," Mr Butykai said, "family pictures, documents, managed pages.
"I don't know what the problem is. I've never done something that is forbidden by the rules."
Another user, Kittii Cserni, said that while she hadn't been affected personally, two of her friends had.
"When they try to register themselves they keep getting blocked out," she told BBC News.
"So many pictures and memories got vanished."
Facebook publishes advice on how to request that disabled accounts be reactivated, on its website.
However, another Hungarian user, Peter Orban, told the BBC he had tried to follow the necessary steps to regain access to his account - but had not yet obtained the desired result.
"I immediately contacted Facebook support, provided them with my ID and all, but I haven't received any response in almost 48 hours now," he said.
He said the problem has affected his work as a social media manager, having been locked out of both Facebook and Instagram since Monday evening.