The executive director of the Coalition for an Airline Passengers' Bill of Rights has filed a lawsuit claiming that her email accounts were hacked by Delta Air Lines.

Kate Hanni said in court documents that she had been in an email exchange with Frederick Foreman, a researcher at a firm called Metron, who was looking into flight delays. She claims that her AOL account was attacked during these conversations, and that some of the emails ended up in the hands of Delta executives.

Foreman had been hired by the Federal Aviation Administration to look into the statistics of flight delays. Metron had cleared him to talk with Hanni, but then fired him after confronting him with the emails, he said.

"When Foreman asked Metron how Metron obtained the information, Metron claimed that Delta had provided them with the stolen emails," said the court documents. "Confirming Metron's claims, the screenshots of the stolen emails presented to Foreman were from Delta. Foreman was fired by Metron the same day. "

Foreman said that the emails he saw covered exchanges between Hanni and himself, as well as between Hanni and her attorney, and emails to journalists.

Meanwhile, Hanni claimed that AOL and Microsoft had confirmed that her PC had been hacked and the password changed. When she did manage to get access to her computer, she found that some files had been copied from her system and that others were hopelessly corrupted.

Hanni is campaigning for an air passengers' bill of rights that would force airlines to provide food, water and medical attention to passengers stuck in planes waiting to take off for more than three hours. She claims that some passengers have spent as long as 11 hours on the tarmac waiting to take off.

Hanni claimed that such a bill, if made into law, could cost Delta around $40m (£24m) a year given the company's record of delays.

Delta has dismissed the charges as "ridiculous", and Metron has denied any wrongdoing.

The case has disturbing similarities with the spying scandal at HP, and a bugging incident at Deutsche Telekom.