Sajid Javid has said the UK Government’s immigration White Paper will not include a "specific target" for reducing the number of migrants coming into the UK.

As the Home Secretary prepared to unveil the full details of Whitehall’s much-delayed post-Brexit plan to end the free movement of workers, Nicola Sturgeon said if it was as expected, then it would be “devastating” to the Scottish economy.

Mr Javid denied Theresa May’s administration was abandoning a key commitment in the Conservative Party General Election manifesto to reduce migrant numbers to the “tens of thousands”.

READ MORE: Westminster's immigration paper "will be devastating for Scotland" says Nicola Sturgeon 

However, when asked, he repeatedly refused to confirm this pledge to get annual net migration down below 100,000.

"There is no specific target. It will be a system that will bring net migration down to more sustainable levels," Mr Javid told BBC Radio 4’s Today programme.

"If you look at the current level of migration, the latest stats show 273,000. Most people agree that is very high, certainly by historical standards.

"In the last two decades it has been in the hundreds of thousands. If you go back further than that it was much lower.

"What we want to do is bring it to a level where it is sustainable in the sense that it meets first our economic need and at the same time, though, it is not too high a burden on our communities or on our infrastructure," explained the Home Secretary.

But the First Minister tweeted: "If the UK Government's immigration paper is as expected it will be devastating for the Scottish economy - our demographics make it essential that we attract people to live and work here.

"A reduction of 80 per cent in people coming here from EU will see our working age population decline.

"Apart from the serious economic damage, these proposals send a terrible message that the UK is becoming less open and welcoming and more insular,” she declared.

Ms Sturgeon continued: "Why any PM would want to claim this as a personal legacy is beyond me.

"In both the development and content of these proposals, Scotland's interests have been ignored.

"If our economy and society are not to be damaged - and the net positive contribution EU nationals make not lost - we need control over these decisions in our own Parliament," she added.

Mr Javid said the UK Government would be consulting further before deciding the minimum salary requirement for high skilled workers applying to come to the UK.

"We are not setting the exact threshold today. There will be a threshold. The MAC [Migration Advisory Committee] suggested it should be £30,000.

READ MORE: Gloom for 200,000 from EU who came to live in Scotland

"That is their view and it is based on their evidence and it is very important for us to listen to that. It is equally important to listen to business to find the right threshold.

"We will consult further on whether it is £30,000 or thereabouts. What is important is that it is the principle that the MAC set out, which is absolutely right, where we want to focus on high skills."

However, the body representing NHS Trusts in England warned a minimum salary requirement of £30,000 for skilled migrants could affect the health service’s ability to recruit the staff it needs.

NHS Providers deputy chief executive Saffron Cordery said they were "deeply concerned" about the White Paper proposals.

"We are deeply concerned about what is going to happen. High skills does not equal high pay," declared Ms Cordery.

"You have got starting salaries for nurses at £23,000; also for paramedics, midwives. Junior doctors starting salaries at £27,000, healthcare assistants at £17,000, all coming in way below that £30,000 cap.

"It is not just health workers, it is social care as well. We have to remember where the skills lay. They lay in those staff under £30,000,” she added.

In announcing the Government’s plans to manage post-Brexit migration, the Home Secretary pledged to "get control over our borders".

Under the blueprint, there will be a new visa route for skilled workers and no cap on high-skilled professions such as doctors and engineers.

Mr Javid said: "We are delivering on the clear instruction to get control over our borders and will bring in a new system that works in the interest of the British people.

"It will be a single, skills-based immigration system built around the talent and expertise people can bring, rather than where they come from - maximising the benefits of immigration and demonstrating the UK is open for business."

The document is also expected to include details of the approach to low-skilled workers. It has been reported they may be able to apply for short-term visas of up to a year.

Confirming that the White Paper will be published following suggestions it may be further delayed, the Home Office said the UK would have full control over who came here with everyone needing permission before they arrived.

This would enable employers to have access to the skills they needed from around the world, while ensuring net migration was reduced to "sustainable levels", the department added.

The new immigration and borders system will be implemented in a "phased" approach from 2021, following the post-exit transition period.

Tomorrow, an Immigration and Social Security Coordination (EU Withdrawal) Bill will be presented in the House of Commons.

As well as measures to end free movement, it creates the legal framework for a future, single benefits system that will apply to both EU and non-EU nationals.

The White Paper was initially due to be published more than a year ago, but it was held back while the MAC carried out a detailed analysis.

It’s report, published in September, concluded that the new system should make it easier for higher-skilled workers to come to the country.

It recommended ministers scrap an annual cap of 20,700 on the number of visas available under the Tier 2 skilled work scheme, and open up the route to "medium-skilled" jobs.

But it said access to Britain's jobs market should be restricted for lower-skilled migrants.

There will be focus on whether the Tory target of cutting net migration to the tens of thousands, which has never been met, is mentioned in the blueprint.

Estimated net long-term international migration to the UK - the difference between the numbers arriving and leaving for at least 12 months - was 273,000 in the year to June.

While EU net migration has fallen, sparking claims of a "Brexodus", the latest figures showed non-EU net migration was at the highest level since 2004.