Investigators say the passengers and crew were knocked out by lack of oxygen and the Helios Airways plane flew on autopilot for two hours before it ran out of fuel and plummeted to the ground near Athens in August 2005.

Petros Clerides, the Cyprus attorney general, described the criminal charges as "among the most serious" allowed under Cypriot law, Kathimerini reported Wednesday.

Nikolas Giasoumis, a spokesman for a group of relatives of the crash victims, said they were disappointed the names of the likely defendants had not been released.

A Greek investigation completed in 2006 blamed the crash on inspectors in Cyprus who did not realize an oxygen gauge was on the wrong setting and on the pilots for not realizing the plane cabin was not getting adequate oxygen.

Relatives have filed 23 lawsuits over the crash.