A 6.1-magnitude earthquake has struck off the south coast of Japan's main Honshu island, the United States Geological Survey (USGS) has said, but no tsunami warning was issued.

The quake hit at 12:22pm local time (03:22 GMT) on Sunday, 644km south of Tokyo, at a depth of 424km, the USGS said.

Japan's Meteorological Agency said there was no risk of a tsunami.

Tokyo and its suburban Kanto region were rocked by minor tremors, but there were no immediate reports of injuries or damage, the agency said.

"We have received no reports of damage to properties nor reports of injuries so far," a spokesman for the Tokyo Metropolitan Police Department said.

The area is prone to earthquakes.

Source: Agencies