The International Atomic Energy Agency (IAEA) is eyeing a mandatory no-fly zones over nuclear facilities, given the magnitude of destruction that might result from a terrorist attack on nuclear reactors, a senior IAEA official said Wednesday.

The issue of safety on nuclear reactors and other nuclear facilities has become a major concern to the U.N. nuclear watchdog agency in the wake of the Sept. 11 suicide hijacking attacks on the United States.

Since then, the Vienna-based agency has stepped up efforts to draw up a rule book on how to safeguard against nuclear terrorism, including measures to ban aircraft from flying over nuclear plants.

An outline of the nuclear safety program is expected to be submitted to an IAEA board meeting on Friday, while specific measures will likely be drawn up by next spring.