Satellite technology will be used to “spy” on homes targeted under Labour’s “mansion tax” council tax surcharge.

The tax-funded Valuation Office Agency (VOA) will pore through aerial photography to help work out which homes in England are the most valuable.

Using the tech, it will work out which homes could be eligible for the new surcharge – aimed at those worth £2million or more.

The VOA will then pass on that data to the Treasury, so it can better hit homeowners with annual tax bills of as much as £7,500 – where a house’s value is higher than £5million.

The agency has been used before, most notably in Wales – where last year it was brought in to verify the sizes of homes and gardens for the Senedd’s own council tax reform.

As well as data from the Land Registry, which keeps a record of house prices over time, the Welsh model monitored homes’ “plot size” by using data from the Ordnance Survey National Geographic Database.

The VOA itself has told The Telegraph it will go as far as inspecting properties in-person “where needed” – and did not deny using “modern technology” in its methods.

But news of the space technology being brought in to line Treasury coffers has sparked uproar from opponents.

Reform UK’s deputy leader Richard Tice said: “So, Labour plan to spy more on the British people.”

Shadow Housing Secretary Sir James Cleverly said: “It’s clear Labour have been using Wales as a test bed to develop the Big Brother technology to hike council tax on people’s homes.

“Labour ministers have failed to deny that the sinister Valuation Office Agency database will be used in England.

“And Labour won’t stop at higher-end homes, you can guarantee that this surcharge will be widened, and families will wake up and find their home is now classed as a ‘mansion’.”

BIG BROTHER BRITAIN – READ MORE:

• Keir Starmer’s ‘dystopian’ digital ID card scheme to cost £1.8BILLION over next three years
• Zia Yusuf tears into ‘Orwellian’ online safety law in stark free speech warning: ‘Plunged into a surveillance state!’
• ‘Intrusive’ new plan could let DWP snoop on claimants’ bank accounts: ‘Completely unprecedented!’
• Patriotic Britons ‘could be DEBANKED just for raising Union flag’ as urgent warning issued

His colleague Dame Harriett Baldwin MP warned the move could fall foul of privacy laws.

There would “definitely be privacy issues around this”, she said, which was “very concerning”.

She added: “This is just a dry run and a dress rehearsal for a complete revaluation of all the council tax bands.”

Sir James had been referencing a statement by Treasury Minister James Murray last year in which he did not rule out using the high-tech VOA model.

Mr Murray hinted at “further investigation and significant preparatory work” before rolling out the Welsh model across England.

While fellow Treasury minister Dan Tomlinson told LBC Labour would consider using “powerful private sector data” to lower the cost of valuing homes.

A VOA spokesman said: “We employ professional valuers who are involved at every stage, using modern technology and industry standard techniques combined with freely available information including sales data, property attribute details and government records.

“We also inspect properties where needed.

“This will be the same for our valuations for the high value council tax surcharge.”