Radioactive powder sent to Japanese PM

Envelopes containing small amounts of radioactive powder were posted anonymously last week to the official residence of Japan's Prime Minister and nine government agencies, police officials said.

Envelopes containing small amounts of radioactive powder were posted anonymously last week to the official residence of Japan's Prime Minister and nine government agencies, police officials said.

At least one of the envelopes, postmarked in Tokyo, contained a message warning that radioactive materials were being sent from Japan to North Korea. Another government official reported receiving a letter containing a sand-like substance.

The residence of the Prime Minister, Yoshiro Mori, received one of the envelopes last Thursday, said the Chief Cabinet Secretary, Mikio Aoki. The envelope held 3g of powder of 1 micro-sievert of radioactivity - too little to harm humans, he said.

Kyodo News agency reported that an initial examination indicated the substance may be ground monazite, a mineral containing thorium, a nuclear fuel material. Whether the mailings were meant to injure anyone was not clear.