Priti Patel has unveiled a US-style digital visa system that she claimed would help the government to count numbers of people entering and leaving the UK accurately for the first time.

People coming to the UK without a visa or immigration status would in the future need to apply for an electronic travel authorisation (ETA), the home secretary said, which automatically determines the eligibility of visitors in advance. The Home Office anticipates about 30 million ETA applications each year.

The proposals to “digitise the border” are to be officially launched on Monday as part of Patel’s widely derided plans to change the UK’s asylum and immigration system. Critics have called her plans to deport asylum seekers back to other European countries incoherent and inhumane.

The digital system is being introduced after recent evidence suggesting that long-held estimates of migration data were significantly wrong.

It was widely accepted that 3 million Europeans lived in the UK and would apply to the government’s EU settlement scheme. By the end of last month, however, more than 5.4 million applications to the scheme had been received, with 4.9 million granted settled status.

Government figures show an estimated 144.7 million passenger arrivals in the year to June 2019, including returning UK residents. About 40 million were from the European economic area and Switzerland; those from elsewhere numbered 20 million.

Patel said: “Our new fully digital border will provide the ability to count people in and out of the country, giving us control over who comes to the UK.”

As well as launching her latest immigration plans, Patel will again stress failings in the asylum system and the need to crack down on people smugglers. On Wednesday she accompanied police as they arrested suspected ringleaders of a people smuggling gang that used minicab and lorry drivers to move migrants in and out of the UK.

However, her asylum reforms have drawn widespread criticism, with the UN among many organisations that believe they are legally unworkable and so damaging they risk Britain’s global credibility.

EU countries have already stated that they will not strike bilateral agreements to facilitate the deportation of refugees from the UK.

The strategy also sets out how the government will make it easier for highly skilled people to come to the UK by simplifying the application process and revamping how people are sponsored by employers.

The Home Office hopes to make entry to the UK fully digital by the end of 2025.