The Ministry of Construction Thursday moved to clear confusion over its new housing development guidelines.

To increase the number of affordable homes and curb soaring prices, the State Council said that from June 1, homes smaller than 90 square metres must account for at least 70 per cent of the total space of residential housing development projects.

However, there has since been no explanation specifying the "90 square metres" and "70 per cent" rules, which many believe are too ambiguous.

For example, in many regions, an apartment of 90 square metres could mean 90 square metres of "usable" area, while in fact it is measured at 110 square metres roughly in floor area.

Such ambiguities have partly delayed the implementation of the measures in most cities and have been perplexing the real estate market, Xinhua News Agency reported yesterday.

The ministry Thursday made it clear that the 90 square metres include both the usable floor space and the shared public space in a residential building.

With regard to the proportion of the smaller houses, the ministry clarified that homes smaller than 90 square metres must account for at least 70 per cent of the total floor space of any new residential building.

It also said the land planned for medium and low price commercial houses must be mainly reserved for the building of homes smaller than 90 square metres. The ratio of such homes must not be breached. Developers must get ministry approval if they change such ratios, the ministry said in a circular issued Thursday.