SINGAPORE - The Housing Board will install window grilles in rental flats on a case-by-case basis, Minister of State for National Development Mohamad Maliki Osman said on Tuesday.

He told Parliament that the tenant must either be a family with children aged 12 years and below, or have household members with medical conditions, such as hyperactivity, intellectual disability or hallucinations.

"There are safety concerns for these families," Dr Maliki said, referring to both groups.

In April, the HDB started to install grilles for families with young children, who form about 15 per cent of the rental population.

It has received about 60 requests in total for grilles and installed 27 over the past two years.

Tenants who do not meet the criteria are advised to seek help from social services offices or voluntary welfare organisations.

Dr Maliki also said that about 75 per cent of the 190 rental blocks have window grilles.

He was responding to questions from Mr Baey Yam Keng (Tampines GRC), who asked why HDB rental flats did not come with window grilles installed, and Mr Png Eng Huat (Hougang), who asked if the HDB would consider making window grilles a standard safety feature for rental flats.