The Procurement Act has received Royal Assent and become law.

The Act aims to deliver simpler, more effective public sector procurement, and help small and medium-sized enterprises (SMEs) secure a greater share of approximately £300bn of expenditure per year.

It is also hoped that the new rules will protect against national security risks in public contracts. High-risk suppliers will be put on a public debarment list and be prevented from bidding for some categories of goods or services, such as areas related to defence and national security.

The Act will require contracting authorities to assess the particular barriers facing SMEs throughout the entire procurement lifecycle, and to consider what can be done to overcome them.

Minister for the Cabinet Office Jeremy Quin said: "We have taken the long-term decisions that will increase our powers to protect our security in our supply chains and procurement.

"This has included radical steps such as creating a National Security Unit for Procurement and giving Ministers the power to prevent suppliers from bidding for certain products where there is a risk to national security it will deliver lasting change which protects the UK for generations to come."

Parliamentary secretary for the Cabinet Office Alex Burghart said: "This Act is all about supporting British business using the opportunity of Brexit, as we change the way government works so it delivers better for people across the country.

"In particular, we draw on the new freedoms available to us by leaving the European Union to embrace and best support our small and medium sized businesses."

The changes are expected to come into force once secondary legislation is laid and after a six-month implementation period.

All public sector contracting authorities will be provided with access to a comprehensive, centrally-funded learning and development package and guidance materials to help them prepare.