TOKYO (AP) -- A fairly strong earthquake with a preliminary magnitude of 6.8 shook northern Japan, but there were no reports of damage or injuries.

The quake, which hit Friday night around 11:21 p.m., was centered about 35 miles under the floor of the Pacific Ocean off the eastern coast of Japan's northern island of Hokkaido, the Meteorological Agency said.

It was felt most strongly in the cities of Kushiro and Nemuro and the towns of Nakashibetsu, Akkeshi and Betsukai in Hokkaido. People in the northern region of Honshu, Japan's main island, also felt the quake.

There was no fear of tsunami, or seismic waves caused by undersea disturbances such as volcanic activity or undersea earthquakes.