The Construction Ministry plans to offer subsidies from fiscal 2001 to encourage owners of major buildings to plant trees and vegetation on rooftops and other parts of their premises to combat rising temperatures in city centers, ministry officials said.

The subsidies will be created through revisions to the Law for the Preservation of Urban Greenery, they said Saturday.

The revisions will be introduced in the next regular Diet session convening in January after the ministry is integrated into the Ministry of Land, Infrastructure and Transport in the government reorganization on Jan. 6.

The primary purpose of the greenery plan is to cool down rising temperatures resulting from the increasing use of air conditioning and from sunlight on asphalt roads in city centers.

The discrepancy in temperatures between centers and suburban areas is thought to cause torrential rains and other undesirable natural phenomenon.

Planting trees and other forms of vegetation is thought to absorb heat.

Currently, some municipal governments have subsidy systems to encourage greenery on rooftops, but they are limited to 2 million yen.

The ministry hopes greater subsidies will encourage vegetation on a larger scale, the officials said.

The ministry is targeting owners of land plots of at least 1,000 square meters within greenery promotion areas that have been designated by municipal governments, the officials said.

Owners must submit greenery plans to local governments, and if they are approved, the central government will pay up to one-third of the entire cost, according to the officials.

Furthermore, if owners meet certain conditions for promoting greenery, they will be entitled to sharp reductions in the fixed asset tax for five years, they said.

The revised law could be applied first to a building in the Shiodome redevelopment area in Tokyo's Minato Ward, which will accommodate the head office of major advertising agency Dentsu Inc., according to the officials. The building, now under construction, is scheduled for completion in 2002.