The Urban Redevelopment Authority (URA) has come up with guidelines to tackle the problem of "shoebox" shops, some of which are smaller than a carpark lot.

The guidelines will require a minimum average retail unit size and minimum corridor widths for all new developments with retail floor area, National Development Minister Khaw Boon Wan said on his blog on Tuesday.

"Lately, a couple of developers who have pushed for shoebox apartments and factories have turned their attention to push for shoebox shops. The URA has received applications from them proposing to build malls featuring mainly shoebox shops, with sizes as small as 9sqm. At 9sqm, the shop will be even smaller than a car park lot," he wrote.

"In many cases, the number of proposed shops in their proposed redevelopments will end up more than 10 times the number of shops in the original malls!" he wrote.

Small shops, such as those catering to certain trades such as florists and moneychangers, have a place in Singapore's retail landscape, he said. "But when they are the predominant shop type in a shopping mall, we have to be concerned about the viability of these shops and the shopping experience of the customers," Mr Khaw noted.

"If these shops are not suitable for most retailers, then the developers' motive is probably to target individual property investors rather than genuine retailers."

He described the guidelines, drawn up in consultation with industry stakeholders such as the Real Estate Developers' Association of Singapore (Redas), as "fair and balanced".

"They give developers and architects the flexibility to propose a suitable mix of larger and smaller shops for their developments."