Marijuana sprouts in Japan prison exercise yard

TOKYO (Reuters) - The grass may be greener on the inside for inmates at Japan's Abashiri Prison, where marijuana shoots have been sprouting in the exercise yard.

Prison official Takashi Nomura said about 300 plants were first found in the yard in July 2006, when staff pulled them out before treating the ground to prevent any regrowth.

But inmates reported finding more marijuana plants last month, and again earlier in August, he said.

Prison officials think soil brought in for the exercise yard may have contained marijuana seeds. Nomura added that no prisoners are thought to have been cultivating the narcotic.

Inmates grow various vegetables at the jail on the northeast side of Japan's northernmost island of Hokkaido, but Nomura said Abashiri had no intention of adding marijuana to the list.

"We only grow potatoes and beans here," he said.