After that, the nationals theoretically could apply for citizenship.

Is there a Russian link?

The visa program has always had its critics, with anticorruption campaigners railing against Britain’s openness to ill-gotten riches from overseas and the foreigners who invest them. But it reached a fever pitch after a former Russian spy, Sergei V. Skripal, was poisoned on British soil with a nerve agent in Salisbury, England.

Prime Minister Theresa May’s government signaled then that it would review the cases of 700 Russians who were granted visas to live in Britain under the Tier 1 visa scheme. Soon afterward, the visa renewal for the Russian billionaire owner of the Chelsea football team, Roman Abramovich, was mysteriously delayed.

Mr. Abramovich later surfaced in Israel, where he had apparently immigrated under the law of return, which guarantees citizenship to any Jew wanting to move there.

What are the problems?

Criticism of the program can be traced as far back as 2014, after visa applications soared. The government’s Migration Advisory Committee filed a report that said the scheme brought limited economic benefits because most of the investors had bought fixed-interest loan securities known as gilts, meaning that they were effectively loaning the government money instead of investing in the country.

“We do not need such investment to fund the deficit. We are selling around £300 million of gilts every day — therefore the capital market is working very efficiently,” the report said.

While investors and their families spend money in Britain and generate revenue, the favorable impacts are typically exaggerated, the committee found. As the benefits were being questioned, the authorities grew concerned over the origins of funds being invested into the country.

This year, the government introduced “unexplained wealth orders,” forcing those suspected of serious crimes to explain the provenance of their wealth and assets.