A disused bottling factory, the former National Aerated Water Company, could be conserved, the Urban Redevelopment Authority (URA) said in an unexpected announcement.

The 62-year-old building near the Kallang River is considered to be one of the last few vestiges of Singapore's industrial past.

Last week, it was sold to Malaysia-listed developer Selangor Dredging for $47 million. The freehold site near the Potong Pasir MRT station can yield 117 apartments.

In response to queries from The Straits Times yesterday, a URA spokesman said: "We recognise the architectural and heritage value of the National Aerated Water Company's building and its role as a landmark in the area.

"This is a private property, and we will engage the building owner to explore the possibility of conserving the building."

Buildings earmarked for conservation need to follow URA's principles of maximum retention, sensitive restoration and careful repair, among other things.

The factory once bottled iconic soft drinks Sinalco, Kickapoo Joy Juice and Royal Crown Cola. News of the sale and potential razing of the two-storey building had caused ripples of concern in the heritage community. A Facebook page called Save The National Aerated Water Company Building was set up.

Several heritage enthusiasts had flagged the Art Deco-styled structure to the URA for conservation in 2007. The site had been zoned for residential use in the country's land use masterplan.

When asked if the news would affect their development plans, a spokesman for Selangor Dredging said the company was "unable to comment on this at this stage".

A reversal of the sale is unlikely. Instead, some sort of compromise between URA and the new owner will have to be found, said Dr Yeo Kang Shua, an assistant professor of architecture and sustainable design at the Singapore University of Technology and Design.

In the 2000s, a bid to conserve Butterfly House mansion in Amber Road - after it was sold - resulted in the retention of features such as the facade, while its iconic curved wings were demolished. In its place rose the 18-storey Aristo condominium.

The latest episode has raised questions of whether the URA should publish a register of sites that are being studied for conservation to give buyers warning on the possible change in building status, said experts.

Singapore Management University heritage law expert Jack Lee said of the possibility of conservation: "It means the developer does not have a free hand to develop the site. Some parts will have to be conserved in some way, and the developer will have to incorporate this into whatever building plans they have."

Reactions to whether the building should be conserved are mixed.

Dr Yeo said that apart from its art deco style, the building's rear features a unique saw-tooth roof structure. "Its clever design allowed a lot of daylight into a very deep factory building, therefore minimising the reliance on electricity," he said.

But several netizens have described the structure as "ordinary", "ugly" and "rundown", and wondered why it should be conserved.

Financial planner Nicholas Lee, 28, said: "To the layman, the building is not outstanding."

The site had been in the hands of the National Aerated Water Company since the 1950s. The building sat dilapidated after operations ceased in the 1990s. Prior to the sale, there was a legal tussle over shares in the factory. The firm was set up in 1929 in Jalan Besar and was once owned by three brothers - Mr Ching Kwong Yew, Mr Ching Kwong Kuen and Mr Ching Kwong Lum.

It later moved to Kallang upon getting the licence to bottle Sinalco, a German beverage, said heritage blogger Jerome Lim.

"The building has been a landmark in the area since the mid- 1950s," he said. "It helps us to recall the industrial past of the Kallang area and the other industries such as the brickmaking kilns and sawmills that were here."

A URA spokesman said it takes a selective and practical approach to conservation, based on a comprehensive list of criteria including the building's architectural, social and historical significance, rarity and contribution to the environment.

"Additionally, we seek views from the building owners and the Conservation Advisory Panel - an independent panel comprising members from the cross-section of the community - before making a decision."

Correction note: An earlier version of the story said Green Spot was one of the soft drinks bottled at the factory. This is incorrect. Green Spot was introduced and bottled in Singapore by Amoy Canning Corporation (Singapore) Limited.