LONDON (Reuters) - Britain commissioned an independent study on Thursday of what role European Union nationals play in the British economy, saying that Brexit would mean new immigration rules, but that there would be no sudden cut-off for workers or employers.

FILE PHOTO: Britain's Home Secretary, Amber Rudd, arrives in Downing Street for a cabinet meeting, in central London, Britain June 20, 2017. REUTERS/Eddie Keogh/File Photo -

As Britain begins negotiations to leave the EU, ministers have said little about the kind of immigration system they want to replace the EU’s freedom of movement rules. That has left companies worried that they may lose access to EU workers.

Interior minister Amber Rudd asked the Migration Advisory Committee (MAC), a public body that advises the government, to look at how migration affects the labor market and the wider economy, and how the post-Brexit rules need to work to support the country’s plans for an industrial revival.

A government statement said Rudd would stress in a letter to the MAC that “there will be an implementation period when the UK leaves the EU to ensure there is no ‘cliff edge’ for employers or EU nationals in the UK.

“Leaving the European Union gives us the opportunity to take control of immigration from the EU. We will ensure we continue to attract those who benefit us economically, socially and culturally,” Rudd said in an emailed statement.

“But, at the same time, our new immigration system will give us control of the volume of people coming here – giving the public confidence we are applying our own rules on who we want to come to the UK and helping us to bring down net migration to sustainable levels.”

Concern about the long-term social and economic impact of immigration helped drive last year’s vote to leave the EU, and the government has a long-standing aim to bring net migration into Britain below 100,000. In 2016, total net migration was 248,000.

But a wide range of companies have expressed concern that they will not be able to hire the people they need to operate, from skilled financiers to unskilled farm workers. The effect could be to force them to relocate.

The government said the MAC, which is expected to report back in September 2018, will be asked to look at a range of issues:

- The current patterns of EEA (European Economic Area) migration, including which sectors rely most on EU labor.

- The economic and social costs and benefits of EU migration to the British economy.

- The potential impact of a reduction in EU migration and the ways in which both business and the government could adjust to this change.

- The current impact of immigration, from both EU and non-EU countries, on the competitiveness of British industry and skills and training.

- Whether there is any evidence that the availability of unskilled labor has led to low UK investment in certain sectors.

- If there are advantages to focusing migrant labor on high-skilled jobs