Britain ordered a year-long study of EU migration on Thursday to help it design a post-Brexit immigration system that is due to come into force just six months after report is completed.
EU citizens' freedom to live and work in Britain will end as soon as it leaves the bloc, scheduled for March 2019, but ministers have said they will design a system that allows businesses to hire the workers they need.
However, with Brexit negotiations already under way and the EU hoping to wrap up talks by October 2018, critics said the study should have been commissioned sooner and that uncertainty was already driving EU nationals out of the UK labour market.
Interior minister Amber Rudd asked the Migration Advisory Committee (MAC), a public body that advises the government, to look at how migration affects the labour market and the wider economy, and how the post-Brexit rules need to work to support the country's plans for an industrial revival.
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, net migration was 248,000.
"The public must have confidence in our ability to control immigration, in terms of type and volume, from within the EU," Rudd wrote in an article for the Financial Times.
"That is why, once we have left the EU, this government will apply its own immigration rules and requirements that will meet the needs of UK businesses, but also of wider society."
Ministers have so far said little about the kind of immigration system they want to replace the EU's freedom of movement rules, leaving companies and workers in limbo and forcing some to make alternative plans.
"The government needs to explain why this study wasn’t commissioned a year ago, directly after the referendum," said lawmaker Ed Davey of the pro-EU Liberal Democrat party, citing lower numbers of EU nurses wanting to work in the health sector.
“Ministers must explain how their negotiations will minimise the damage Brexit will do to our economy and public services.”
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".
Rudd said the government would "set out some initial thinking on options for the future immigration system" later this year.
Immigration minister Brandon Lewis said the MAC would make interim reports, and that its work was not the only source the government would use to design its new immigration system.
A wide range of companies have already 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.