LONDON (AP) — Want to see Big Ben? Better make sure you’ve got some cash on hand if you’re visiting from a "high risk" country.

British deputy leader Nick Clegg says his government is studying the idea of an immigration insurance plan which would see visitors from unspecified high risk areas of the world put up a cash deposit to come to the U.K.

The bond — the amount of which still hasn’t been determined — would be repaid only upon departure. Visitors would lose their deposit if they overstay their visas.

Immigration is a sensitive topic in Britain, which has seen a surge of arrivals from Eastern Europe. The government has pledged to reduce net immigration to the tens of thousands.

Clegg laid out the proposal in a speech Friday.