Liz Truss has pledged to boost UK growth rates with “full-fat freeports”, in the latest policy proposal to emerge in the Tory leadership campaign.

The Foreign Secretary, who is currently tipped as the frontrunner to replace Boris Johnson, has promised to cut red-tape and boost investment as part of her bid to defeat rival Rishi Sunak.

The latest flagship policy from her campaign may also be seen as a bid to steal a march on Mr Sunak, who has been an advocate of free ports since his days as a backbench MP and has used the contest to style himself as the “common-sense Thatcherite” candidate.

The plan from Ms Truss, seen as the candidate of the Tory right-wing and as the most popular with the grassroots, comes with fresh promises of reducing regulation and cutting Whitehall bureaucracy.

Pitched as the cornerstone of her tax-cutting economic vision, the Truss campaign said that the plans would see brownfield sites and other locations turned into “investment zones”, dubbed “full-fat freeports”.

“As Prime Minister, I will be laser-focused on turbocharging business investment and delivering the economic growth our country desperately needs.

“We can’t carry on allowing Whitehall to pick the winners and losers; like we’ve seen with the current freeport model,” Ms Truss said.

Freeports became one of the flagship, post-Brexit policies for the Johnson Government, with several free port locations announced by then-Chancellor Mr Sunak last year.

In a think-tank report in 2016, the then-junior Tory MP wrote: “Brexit will provide the UK with new economic freedom, and the Government should take the opportunity to create Free Ports across the nation.”

The aim is to boost economic activity near ports or airports, with the sites benefitting from tariff exemptions on imports.

Under her plan, Ms Truss said that the investment zones would benefit from a low-tax burden, reduced planning restrictions and regulations tailored on a case-by-case basis.

She also ties the plan into the Johnson Government’s levelling-up pledge, claiming that the investment zones will create new model zones akin to Saltaire and Bournville.

In what might be seen as an implicit criticism of the former chancellor’s record, Ms Truss also says that she will reform current Government policy to “unleash the potential” of current free ports.

“By creating these new Investment Zones we will finally prove to businesses that we’re committed to their futures and incentivise them to stimulate the investment that will help deliver for hardworking people,” she said.