Iranian rescue teams battled severe weather Monday as they searched for the wreckage of a passenger plane that disappeared high in the Zagros mountains the previous day with 66 people on board. Several helicopters that had deployed at dawn to hunt for Aseman Airlines flight EP3704 were forced to return to base, officials said. "Unfortunately due to strong winds and fog reducing visibility, it was not possible for helicopters to continue their search," a Red Crescent official told the ISNA news agency. The deputy governor of Kohgiluyeh and Boyer-Ahmad province was quoted by state media as saying the wreckage was found near Dengezlu city, in Semirom county, in Isfahan province. A few minutes later, Irans Civil Aviation Organisation said it could not confirm the wreckage had been discovered. Officials said hundreds of mountaineers, supported by dogs and drones, were operating around the 4,409-meter Dena mountain. The ATR-72 twin-engine plane, in service since 1993, flew early Sunday from Mehrabad airport towards the city of Yasuj, some 500 kilometers to the south. The planes emergency locator transmitter was reportedly not functioning, helping to explain the difficulty in finding the wreckage. A team of crash investigators from French air safety agency BEA was set to arrive in Iran later on Monday.