In an extremely rare move, the Upper House Steering Committee said Friday the chamber will no longer allow Taro Yamamoto, the anti-nuclear lawmaker who made a public stir by handing a letter to Emperor Akihito, to participate in any event hosted by the Imperial family.

During a garden party last week, Yamamoto, a former actor known for his radical anti-nuclear rhetoric, handed a letter to the Emperor outlining what he believes are problems caused by radioactive fallout from the wrecked Fukushima No. 1 power plant.

Yamamoto was criticized for attempting to use the Emperor for political purposes, which is generally considered forbidden under the Constitution.