Seven blocks of flats in Greenock are to be demolished after they were found to contain potentially dangerous concrete.

The properties, on Belville Street, contain Raac - reinforced autoclaved aerated concrete - and now River Clyde Homes (RCH) has said they have to be knocked down.

The Health and Safety Executive (HSE) previously warned that Raac was now beyond its lifespan and could "collapse with little or no notice".

Dozens of homes are contained within the four-storey blocks, known locally as The Stilts.

Raac was first discovered in five of the blocks in 2024.

Some of the people affected are homeowners while others are renting. Most tenants have already been rehoused.

Residents have been invited to a meeting with RCH on Tuesday evening.

A letter from River Clyde Homes to residents, seen by the Greenock Telegraph, said: "Ultimately, RCH wishes to establish a wider regeneration plan for the Belville Street area with all stakeholders and partners.

"Unfortunately, that regeneration plan cannot include the retention of the affected Belville Street blocks."

The letter added that the housing association planned to "explore potential solutions" to support the owner-occupiers in the block.

A spokesperson for RHC said it was "an extremely difficult and unsettling situation".

They added: "Following extensive technical assessments and consideration of all available options, we have written to those affected and are meeting with residents to ensure they have the opportunity to discuss the issues raised, and for us to answer questions directly."

The spokesperson said RCH was working closely with Inverclyde Council and other stakeholders, adding: "We recognise the pressures on housing locally and will continue to work constructively with all agencies to support residents throughout this process."

The flats were built in the mid-1960s using an unusual design to cope with the steep hillside.

They are elevated at the front by concrete pillars with garage space beneath the properties.

Inverclyde Council transferred its housing stock to River Clyde Homes in 2007 and no longer owns any of the properties.

Raac stands for reinforced autoclaved aerated concrete.

It is a lightweight material that was used mostly in flat roofing, but also in floors and walls, between the 1950s and 1990s.

It is a cheaper alternative to standard concrete, is quicker to produce and easier to install.

It is aerated, or "bubbly" - like an Aero chocolate bar.

But it is less durable and has a lifespan of about 30 years.

Its structural behaviour differs significantly from traditional reinforced concrete.

It is susceptible to structural failure when exposed to moisture and the bubbles can allow water to enter the material.

If that happens, any rebar reinforcing Raac can also decay, rust and weaken.

Because of this, Raac is often coated with another material, such as bitumen on roofing panels. But this material can also degrade.

The Health and Safety Executive (HSE) said Raac was now beyond its lifespan and could "collapse with little or no notice".