The land, totaling some 4.1 million hectares, is larger than the county's Kyushu southwestern main island, according to the panel, chaired by former Internal Affairs and Communications Minister Hiroya Masuda.

Of some 230 million lots of land registered in the country, some 20.3 pct are unattended, the panel estimated. It calculated the figure on the basis of a survey by the land ministry, taking into account information including on population data.

The estimate was the first such nationwide figure based on state data.

The land lots are not used effectively or taxed properly, the report pointed out.

In its sample survey earlier this month, the Justice Ministry said 6.6 pct of land tracts in urban areas and 26.6 pct in the rural areas may now be unattended.

The panel will study solutions for the issue further and make proposals this autumn.

In Japan, land ownership information is registered in the real estate registry records, but owners are not obliged to register or update such information.

If owners leave their ownership information intact for generations, the number of inheritors is multiplied.

When the state or local governments buy such unattended land plots for disaster reconstruction or road maintenance projects, they need to find and get approval from all inheritors.

The panel pointed to shrinking land demand and asset values due to Japan's low birthrate and declining and aging population as a reason for the increase in unattended plots. (Jiji Press)