British Prime Minister Rishi Sunak unveiled plans Friday to create two "green" free ports to attract post-Brexit business and jobs to Scotland, whose leaders are agitating for independence.

Sunak, fresh from what he called robust but constructive talks with Scottish First Minister Nicola Sturgeon, announced a drive to bolster investment two years after Britain's exit from the European Union.

His Conservative government will spend up to £52 million ($63 million) on the ports, which are located in Inverness-Cromarty Firth Green and in Forth Green.

The facilities will help Scotland "create jobs, drive growth and level up the country", the UK government added in a statement.

Free ports -- similar to free zones or enterprise zones -- are specially designated areas, usually found near ports or airports.

They are considered to exist outside the host country's normal tax and customs territory, like duty-free shopping zones.

The news comes amid tensions with London staunchly opposed to attempts by Sturgeon's nationalist government to hold a new independence referendum.

"We've got lots of challenges that we all face collectively around the UK -- and where we can work together and make a difference we should," Sunak told the BBC in Scotland.

"Today's announcement of our two new green free ports in Scotland is a great example of that."

Officials said the ports qualified as "green" because they will aim to attract businesses focussed on renewable energy including offshore wind as well as carbon capture.

Sturgeon's Scottish National Party (SNP) had wanted to hold a second independence plebiscite in October, but this was blocked by Supreme Court judges in London.

Instead, the SNP says it will turn the UK's next general election likely next year into a de-facto referendum for Scotland.

Scots voted narrowly in 2014 to remain part of the union, but this pre-dated the UK's controversial 2016 referendum to leave the EU.