Found in the tweets by @Casey_Matsuoka (in Japanese):
Prime Minister's Assistant Hosono live on BS Asahi. He said from March 11 to March 22 hardly any of the [radiation] monitoring posts were working, and they were using data from remote observation points to guess the radiation level at the plant. In other words, the government and TEPCO were insisting on safety without any solid data.
"BS" stands for "Broadcasting Satellite", although I wouldn't blame you for thinking about something else.
And this BS coming out of Mr. Hosono (from Casey's tweet), more than 1 month since it happened:
"After the explosion of Reactor 1, we [the government, TEPCO] wanted to prevent hydrogen explosions but had no means of doing so. We thought it [hydrogen] leaked from the Containment Vessel and it was the core meltdown, but we just didn't feel like announcing that."1号機が爆発後、水素爆発を防ごうとしたが手立てがなかった。格納容器からの漏れでありメルトダウンと考えていたが、そう積極的に発表する気分にはなれなかった。
So, I ask again: who's been spreading baseless "rumors", or 風評 (wind rumors)?
Oh by the way, speaking of the core meltdown, NISA spokesman Koichiro Nakamura was replaced after he spoke of the possibility of the core meltdown in Reactor 1 in his press conference on March 12, at the express and angry demand from the Prime Minister himself. (News Post Seven, in Japanese)
Prime Minister Kan is considering naming Mr. Goshi Hosono as Minister in charge of dealing with the Fukushima I Nuke Plant accident.