London: Britain is building a database of over 60,000 wealthy foreigners, including Non-Resident Indian (NRI) industrialists, living in the UK, signaling that the Government will close the net on expatriates trying to escape billions of Pounds in tax on their overseas income.

According to official sources, the Inland Revenue has begun sending out letters to 6,500 employers asking them for information on "inward expatriate employees who are non-domiciled". These are mostly foreigners working in the UK who do not pay tax on foreign earnings because they are not brought into Britain.

The taxman has set up five units at tax districts across the country to collect personal details, such as names and national insurance numbers.

Recently the rule has kept NRI steel industrialist Lakshmi Mittal, Greek shipping magnates such as the Niarchos and Embiricos families, and the new influx of Russian billionaires out of the clutches of the Revenue.

Some estimates put the annual tax loss at 5 billion Pounds but accountants argue that a change in the rules would deprive the Treasury of upto 10 billion Pounds in lost revenues if wealthy foreigners decamped.

The Revenue has no way of knowing how many expatriates and non-domiciles work in Britain - the only information available to the taxman comes through the self-assessment system.