Multiple incidents of people using counterfeit tests results to work around coronavirus restrictions laid out by various countries have been reported in recent weeks.

Last week, French police arrested six men and one woman who were selling falsified negative test results at Charles de Gaulle Airport in Paris. All seven were charged with forgery, use of forgery and complicity in fraud.

The fake testing certificates showing a negative coronavirus diagnosis were allegedly going for about $180 to $360 a piece.

The practice of selling fraudulent results has been observed in other countries as well, including the U.K. and Brazil, where four tourists were caught allegedly using counterfeit documentation to travel via private jet to Fernando de Noronha, an archipelago off the coast. The islands currently require negative coronavirus test results from within a day before entry, The Washington Post reports.

A U.K. man recently spoke told the Lancashire Telegraph about how he was easily able to travel to Pakistan with counterfeit test results by obtaining a negative certificate from a friend.

“You can simply get their negative test and change the name and birthdate to your own," he said. "You also put a test date on which is within the time limit required. You download the email, change it and then print it."