New measures have come into force requiring businesses that bid for major government contracts to commit to achieving net zero emissions.
The rules, which came in last week, will apply to any companies bidding for government contracts worth more than £5m a year, not just those who are successful.
On the public sector client side, the measures apply to all central government departments as well as their executive agencies and non-departmental public bodies.
Cabinet Office officials said the UK was the first country in the world to put this type of measure in place, helping deliver the Government's legal duty to reach net zero carbon emissions by 2050.
'Government spends £290bn a year on procurement and it’s right that we use this spending power to green the economy,' the chancellor of the Duchy of Lancaster Steve Barclay said.
A carbon reduction plan sets out where an organisation’s emissions come from and the environmental management measures that they have in place.
Some large companies already self-report parts of their carbon emissions, known as Scope 1 (direct) and Scope 2 (indirect owned) emissions as part of the Streamlined Energy and Carbon Reporting regulations published in 2018.
The new rules will go further, requiring a commitment to achieving Net Zero by 2050 at the latest, and the reporting for the first time of some Scope 3 emissions; including business travel, employee commuting, transportation, distribution and waste.
Andrew Griffith, UK net zero business COP champion, said: 'The message to businesses is clear - engaging on net zero is no longer an option but a necessity from today, with businesses large and small now needing firm climate plans and commitments in place to supply major government contracts.
'As we prepare to host the UN COP26 Summit this is exactly the type of leadership and collaboration required from government and business to show the world that we are serious about investing in a greener, more prosperous future.'
The CBI’s director of decarbonisation, Tom Thackray, said: 'The scale and breadth of spend makes public sector procurement an essential tool in driving net zero progress across all sectors and regions of the country. This new policy will provide a sharp focal point for public-private partnerships.'