New Housing Board estates and private condominiums may soon be required to provide a stipulated amount of greenery on their sites.

These could take the form of landscaping, rooftop gardens, or vertical greenery like green walls.

Minister of State for National Development Desmond Lee said on Thursday that the Ministry would be exploring the possibility of introducing a minimum requirement, as a way to ensure "pervasive" greenery continues to exist in Singapore.

"Where new developments displace existing greenery, (they) should fully or partially replace the lost greenery by other means," he added.

He said that MND will also study how to add more greenery to public infrastructure such as sheltered walkways and bus shelters. No further details were available at this stage. Mr Lee was speaking at the International Skyrise Greenery Conference held at the Singapore Expo on Thursday part of the inaugural GreenUrbanScape Asia exhibition.

New developments in certain parts of the historic civic district, financial district, and Jurong East have already been required to replace greenery lost during development, under guidelines introduced by the Urban Redevelopment Authority in 2009.

Other government incentive schemes such as the Skyrise Greenery Incentive Scheme also exist to encourage developers to green their buildings, as part of the country's City in a Garden vision.

Today, sky gardens and vertical green walls adorn more than 500 buildings here. Singapore has some 60 hectares of green roofs, exceeding Chicago, which leads the United States with 51 hectares.