Russian airline Aeroflot cancelled dozens more flights on Tuesday but said it had now stabilized its schedule after a major cyberattack a day earlier, and the transport ministry said the issue had been resolved. Two pro-Ukraine hacking groups claimed on Monday to have carried out a year-long operation to penetrate Aeroflot's network. They said they had crippled 7,000 servers, extracted data on passengers and employees and gained control over the personal computers of staff, including senior managers. Aeroflot's online timetable showed about 25 flights out of Moscow's Sheremetyevo airport had been cancelled on Tuesday, mostly overnight and through the morning. Nearly all afternoon and evening flights were due to take off, though dozens were delayed. Interfax news agency said 31 inbound flights to the capital had been cancelled. Aeroflot said it had "stabilized" its flight program. The transport ministry said in a statement: "Thanks to the efforts of Aeroflot employees, with the active support of Sheremetyevo services, the problem that arose was resolved in the shortest possible time." The ministry described the issue as "a failure in the IT infrastructure". It did not refer to it as a cyberattack, although prosecutors have said they are investigating it as such. Responsibility was claimed by the Belarusian Cyber Partisans, a long-established group that opposes President Alexander Lukashenko, and by a more shadowy and recent hacking outfit that calls itself Silent Crow. ‘Saving face’ Yuliana Shemetovets, a spokesperson for the Cyber Partisans, said Aeroflot was likely working with costly manual systems in order to maintain the appearance of business as usual. The ministry statement said there had been a "transition to domestic systems".