China’s national security agency in Hong Kong spent HK$508 million ($65 million) on a luxury villa in an exclusive neighbourhood perched on a hill above the city, registry data has revealed.

The purchase last month offers a rare glimpse into an organisation which was set up in the Chinese finance hub more than two years ago but remains opaque and free from public scrutiny.

The Office for Safeguarding National Security of the Central People’s Government in the Hong Kong Special Administrative Region was listed as the buyer of the largest villa at the Mont Rouge residential project in the Beacon Hill district, according to a Land Registry document.

The 666-square metre (7,171-square foot) mansion has five bedrooms, three car parking spaces, a garden, its own lift and is described by its developer as “a residential jewel that secures panoramic views, low density and luxuriant living”.

The sale set a record for the most expensive house sold in the Kowloon district on a per-square foot basis, according to local media.

Beijing’s national security office in Hong Kong was established in July 2020 following huge and sometimes violent democracy protests, alongside the imposition of a sweeping security law which has since ensnared more than 200 people, including many of the city’s best known democracy activists.

The security law empowered China’s mainland security apparatus to operate openly in Hong Kong for the first time where their agents can conduct their own investigations and are not bound by the city’s laws.

The office requisitioned two hotels on Hong Kong’s main island to be its temporary headquarters, while an 11,500-square metre government plot has been earmarked for a permanent base.

A Hong Kong government spokesperson said the national security office is funded directly by the central government.

Hong Kong has been rated the world’s least affordable place to buy property for multiple years by the Demographia International Housing Affordability, outstripping famously pricey cities like Sydney and Vancouver.

According to Demographia, it would take 23.2 years for a local resident to buy a home even without spending any of their income.

The city’s sky-high property prices have taken a hit in the last six months, weighed down by Covid curbs, political turmoil, population outflow and dampened mainland China demand.

But rising interest rates have made mortgages for the average resident become more expensive, impacting affordability even as the property market slides