LONDON — A leaked document published Wednesday sheds some light on the British government’s plans to cut immigration from the European Union once Brexit has become a reality.

The draft Home Office document published by the Guardian newspaper reveals plans to make it much harder for low-skilled EU workers to settle in Britain. It would also make it tougher for EU workers in Britain to bring in family members to join them.

It emphasizes the need to put British workers first and to judge immigration on whether it benefits society as a whole, not just the migrants.

Many who backed Brexit in the 2016 referendum were motivated by a desire to lower immigration levels. Prime Minister Theresa May’s government has so far revealed few details about how it plans to cut immigration numbers, so the draft document offers some insight into how the Home Office hopes to deliver on the Brexit promise to “take control” of Britain’s borders.

The prime minister told Parliament Wednesday it is important to keep immigration at a “sustainable” level as she claimed uncontrolled immigration depresses the wages of people at the lower end of the income scale.

May also said immigration has an impact on access to service and access to infrastructure that must be controlled. She insisted Britain will still “welcome the best and the brightest here to the United Kingdom.”

Nicolas Hatton, a French resident of Britain who leads a group fighting for the rights of EU nationals in the UK, said he was “horrified” that Britain is turning its back on tolerance in favor of solutions that will create problems for hundreds of thousands of people.

The 82-page document, marked “official sensitive,” does not represent finalized government policy and has not been approved by ministers. It has been circulated among senior government officials.

The plans may be changed extensively after discussions with Parliament and with EU officials, who will determine how British citizens living and working in EU countries are treated after Brexit.

According to the paper, potential migrants will be required to register with the Home Office for a residency permit that would last up to two years, with possible longer terms granted for highly skilled workers. The paper says tightening the legal definition of an extended family is also being considered to reduce the number of relatives being brought in.

It suggests the new restrictions would come into force as soon as Britain formally leaves the European Union, which is expected early in 2019.

The leaked plan drew immediate condemnation from some corners, including the food and drink industry and a prominent agricultural union.

Ian Wright, director of the Food and Drink Federation, said it showed a “deep lack of understanding” of the contributions made by EU migrant workers.