At least a million people illegally downloaded the season premiere of “Prison Break” — and Fox isn’t pleased.

According to the website Torrentfreak, “Prison Break” immediately became one of the most downloaded shows on BitTorrent after Fox aired the series’ fourth season premiere on Monday.

The 20th Century Fox TV-produced series is available on News Corp.’s Hulu service via free streaming — but Fox believes much of the unauthorized “Prison Break” downloading is taking place overseas, where access to Hulu’s video service remains blocked.

That led News Corp. to issue a warning to international pirates this week: “Our litigation strategy against BitTorrent in the U.S. has been successful, and we’ve managed to shut down the major pirate sites,” the conglom said. “We are pursuing similar strategies internationally and anticipate success there as well.”

Fox insiders hope the introduction of an international version of Hulu — a joint venture between News Corp. and NBC Universal — will also put a dent in the downloads. News Corp.’s Peter Chernin said this summer that an international version of the popular video website will eventually be rolled out.