Two volcanoes erupted near major cities in Japan on Monday, with one spewing white smoke and ash into the heart of Tokyo, the weather agency said.

Authorities advised residents to wear masks in the towns near Mount Asama, some 150 kilometres (95 miles) northwest of Tokyo, which belched lava shortly before 2:00 am.

The 2,568-metre (8,425-foot) volcano last erupted in August last year. Live television footage showed smoke coming from the snow-covered mountain hours after the eruption.

No one was injured.

Carried by winds, volcanic ash fell like snow flakes on towns at the foot of the mountain. Traces of ash were even reported in central Tokyo and all the way in the metropolis of Yokohama southeast of the capital.

"I've been a taxi driver in Yokohama for 10 years but I've never seen this kind of volcanic ash before," the driver said on television as he wiped a thin blanket of ash off his windshield.

"I heard a rumbling and my windowpanes kept rattling," said a female resident of one of the towns near the volcano where local officials urged inhabitants to wear masks.

The weather agency warned of a possible fall of rocks within four kilometres of the crater.

Meanwhile, 1,117-metre (3,686-foot) Mount Sakurajima next to the southern city of Kagoshima erupted eight times, the meteorological agency said, warning of falling ash.

But local inhabitants and city officials said daily activity was little affected by the eruptions which occurred from Sunday evening until early Monday, the agency said.

"Most of the ash has fallen into the sea, and we did not note anything out of the ordinary affecting daily activity," said Hiroyuki Ikenoue, a local official.

Japan lies at the convergence of four tectonic plates, subjecting the nation to frequent volcano eruptions and 20 percent of the world's powerful earthquakes.