Visitors from 11 countries - including South Africa - could be forced to get a visa before coming to Britain, it was announced.
Immigration minister Liam Byrne said the countries will be required to make a range of improvements if their citizens are to avoid tough visa rules, including compulsory fingerprinting.
The countries are South Africa, Trinidad and Tobago, Brazil, Malaysia, Venezuela, Bolivia, Botswana, Lesotho, Mauritius, Namibia and Swaziland.
In 2006, more than 450,000 visitors came to the UK from South Africa alone - the fifth largest group of visitors to Britain after the US, Australia, Canada and Japan.
In the same year more than 180,000 visited from Brazil, 176,000 from Malaysia, and more than 35,000 came from Trinidad and Tobago.
The countries have until the end of the year to prove to the Home Office they have taken steps to tighten passport security, protect against crime and terrorism, co-operate over deportations from the UK and worked to combat immigration abuse.
Mr Byrne said: "Three quarters of the world's population need to pass a visa check to come to Britain.
"We cannot and will not shy away from going wider and will wherever we think there's a risk to the UK."
A final decision on imposing visa requirements on the nations - seven of which are members of the Commonwealth - will be made early next year.
