A strong earthquake with a magnitude of 6.1 struck off the northern Japanese coast Monday, but there was no danger of a tsunami, the nation's weather agency said.

The quake occurred at 8:30 p.m., about 20 miles below the ocean's surface off the northern coast of Fukushima, the Meteorological Agency said.

The agency said there was no danger of a tsunami, or seismic waves, from the quake, which was also felt slightly in Tokyo and its vicinity.

There were no immediate reports of damage or injuries, according to a police official in Miyagi, one of the areas where the quake was felt most strongly.

Miyagi was among the worst-hit areas when a 7.2-magnitude earthquake struck last month, killing at least 12 people, leaving 10 others missing and injuring more than 300 people.

The police official, however, said Monday's temblor "was almost nothing" compared to the one in June.

Japan is one of the world's most earthquake-prone countries.