The Planning Authority has approved an extension to the Quad Towers high-rise project in Mrieħel.

The extension will increase the total floor-space of the project by around 20 per cent - from around 42,000 to 51,000 square metres - and adding an underground car park, supermarket and other commercial uses. The building height will remain unchanged.

The €70 million Tumas and Gasan holdings project, comprising four interlinked towers of between 14 and 19 storeys each, was controversially approved by the PA in 2016, prompting an appeal by environmental groups. The appeal was rejected by the review tribunal in May, confirming the permit.

NGOs had argued that Mrieħel had not been included in the policy regulating high-rise buildings when it was issued for public consultation, meaning that the public did not have the opportunity to comment on whether it was appropriate site for such projects.

Objectors also argued that the Quad Towers would have a negative impact on historically important views from Mdina and Valletta.

While the newly-approved extension was in itself largely uncontroversial, photomontages submitted by the developers as part of the new planning process reignited concerns over the overall visual impact.

The new renderings appeared radically different to those produced by the same consultants for the original development, with the towers appearing from viewpoints in Mdina and Valletta far closer and more prominent than they originally did.

The montages more closely resembled renderings prepared by NGOs to showcase what they said was the true scale of the project, which developers had dismissed as exaggerated.

The difference was due to changes in the PA’s guidelines for photomontages implemented after the main project was approved, but raised questions over whether the public had been given a mistaken impression of the four towers’ visual impact during the application process.