Employers across the country are to be given an EU citizen “toolkit” to help staff from the bloc to register for a new immigration status that will be legally required after Brexit.

The Home Office unveiled a package of briefing packs, posters and leaflets at an event involving representatives of some of the biggest employers and groups campaigning to preserve the rights of the estimated 3.5 million to 3.8 million EU citizens living and working in the UK.

The campaign group the3million said the government was putting “the cart before the horse” with the launch, given that EU citizens and Britons on the continent still had no legal guarantee of their status post-Brexit.

“Eight in 10 EU citizens [in the UK] are of working age so I understand why the government is focusing on employers with this toolkit but it’s all very premature when the withdrawal agreement is still being negotiated,” co-founder Nicolas Hatton said.

He pointed out that a live trial for registering EU citizens was only being launched on 28 August with the full scheme not rolled out until next year. The Home Office announced its plans for the pilot scheme last week, which will run in the north-west, and said it was looking for 4,000 recruits in universities and the NHS.

Sajid Javid, the home secretary, said the toolkit, which will be available on the gov.uk website, would “offer security and certainty to EU citizens living in the UK” and would help all EU citizens living in the country “get their new immigration status”.

The Home Office unveiled its settled status scheme last month but recent declarations that the government was preparing for a no-deal scenario has fuelled fears among EU citizens.

The new Brexit secretary, Dominic Raab, told a select committee on Tuesday that EU citizens would not face mass deportation if the UK crashed out of the bloc.

Raab promises if there is no deal EU citizens will be safe. Legal assurance will be given through Home Office legislation. "There would be no wholesale removal of EU nationals or removal of their rights. " — lisa o'carroll (@lisaocarroll) July 24, 2018

Among the employers and groups at the launch on Tuesday were the British Retail Consortium, the Confederation of British Industry, the pharmaceutical corporation GSK, Universities UK and Tech UK and the East European Resource Centre, a small charity in London that has recently expressed concern about vulnerable groups struggling to register for the new “settled status”.

These range from agricultural workers in Lincolnshire who do not speak English and do not consume British media to the elderly. It includes people in care and people in cash-in-hand domestic employment who will have no paperwork as evidence of their legal right to remain in the UK post-Brexit.

Matthew Fell, the CBI’s chief UK policy director, said it would be asking all its members to share the new toolkit.

All EU citizens living in the UK up to and, for a limited period, beyond Brexit day will be eligible to apply for “settled status”.

The Home Office has been working with business and EU citizens campaigners to develop a system that it hopes will not result in any Windrush-type scandal decades down the line. But it has faced criticism that the scheme is not optimised to reach everyone and will be prone to error, with consequences including deportation.

Earlier this week the Brexit committee called on the Home Office to issue “settled status” paper documents to allow EU citizens to demonstrate to employers and landlords that they were legally in the country to deter potential discrimination.