A government source said the Tier 1 investor visa scheme will be closed by the home secretary, Priti Patel.

Those who invest at least £2m in the UK are offered residency through the scheme.

Prime Minister Boris Johnson earlier this week said he was working on deterring Vladimir Putin's allies from benefitting from the UK economy as Russia amasses troops on Ukraine's border.

Follow live updates on the Ukraine-Russia crisis

The source told Sky News: "There are security concerns about this route and we have been considering closing it for some time.

"The home secretary is very conscious of the effects of money-laundering and dirty money in the UK and that's why she's pushing to close it.

"Legitimate applicants will be able to apply to come to the UK through other routes."

The Tier 1 investor visa is dubbed the "golden visa" as it allows those with substantial amounts of money to gain a visa for them and their family quickly and they are then free to work and study in the UK - or do neither.

Unlike other visa categories, there is no minimum amount of time visa holders have to spend in the UK to preserve their status, although it does lapse after a two-year absence.

It can also be extended indefinitely, provided the investment is maintained, and provides a direct route to UK permanent residence.

The majority of golden visa holders are from Russia and China.

A significant number of Russian oligarchs have bought homes in London - dubbed Moscow on Thames by some - with many known to have permanent residency.

Under Mr Putin, many more Russian businesspeople have become oligarchs than under previous Russian leaders, with the president allowing them to maintain their powers in exchange for explicit support for him.

The golden visa was launched in 1994, and in 2015 and 2019 requirements were tightened after it was found the scheme was at risk of being used for money laundering.

On Thursday morning, Armed Forces Minister James Heappey told Sky News Russia is placing more troops on its border with Ukraine, despite Moscow saying they were pulling back.

As the UK, with NATO allies, tries to prevent an invasion, Mr Heappey said the UK is "entering into a new period of Russian relations...a new period of sustained competition between the West and Russia that probably will last for a generation or more".

As a result, he said parliament is bringing forward measures to "strengthen our ability to sanction Russian oligarchs and deny them financial gain in the UK".

Follow the Daily podcast on Apple Podcasts, Google Podcasts, Spotify, Spreaker

Mr Heappey added: "The message to Moscow is that the price to Russia as a country, in terms of state-on-state sanctions but it's a reflection of Russian politics that this may matter more.

"The cost to the elite around President Putin and those oligarchs that own all of these vast companies and have had the world as their oyster for so long.

"If President Putin continues on the course of action that he's on then the UK will not be alone in making it extraordinarily hard for those individuals to enjoy the trappings of their wealth in the West. "