TOKYO, April 21, 2009 (AFP) - A 5.0 magnitude offshore earthquake shook northern Japan on Tuesday, but there were no immediate reports of casualties or damage, officials said.

Japan's meteorological agency said there was no risk of a tsunami from the quake, which hit at 6:58 pm(5.58pm Singapore time).

The quake hit about 40 kilometres (25 miles) beneath the sea floor in the Pacific Ocean off Fukushima prefecture.