Japan's meteorological agency on Tuesday issued a warning to limit access to the popular hot springs resort of Hakone after a nearby volcano became active and began belching steaming gas.

Two minor quakes measuring magnitude 2.0 and 2.4 were recorded Tuesday morning at the volcano, southwest of Tokyo, the agency reported.

"Activity at Hakone... is in a state of uncertainty," the agency said in an advisory.

"There is a possibility that a minor eruption may suddenly occur," it said. "Please do not enter dangerous zones."

The warning, which comes in the middle of the nation's "Golden Week" spring holidays, was expected to affect tourism there as some 20 million people, including foreign tourists, visit Hakone, one of the most famous hot spring resorts in Japan, every year.

The agency issues restraint advisories when a volcano becomes sufficiently active to spew lava, ash, hot steam and toxic gas as well as rocks and ash.

Japan sits on the Pacific "Ring of Fire", where earthquakes and volcanic eruptions are relatively commonplace.

Last September, a volcano violently erupted in Mount Ontake, central Japan, leaving 57 people dead and six others still missing in the nation's deadliest eruption for almost 90 years.