Britain is introducing stricter rules on so-called golden visas as part of a crackdown spurred by the Skripal nerve agent attack last year in Salisbury.
The Financial Times reported that in an attempted crackdown on money-laundering, new Home Office rules that take effect in April will require visa applicants to prove they have had control of more than £2m for at least two years, rather than 90 days.
Home Office officials also said the department was still looking into the idea of wealth audits, but they would not be included in the April rule changes.
The investments will also need to be made in UK businesses, while investing in gilts will be excluded, in an attempt to increase the benefit to the British economy.
On the other hand anti-corruption charity Transparency International UK, said the proposals were far more modest than those first envisaged by ministers.