Tensions grew as the colonial government tried to restrict Chinese migration through deportations.

Thereafter, Qing authorities began to restrict inward migration to the city.

Controlled borders restrict migration by non-citizens.

Demographers also expect strains on the household registration system, which restricts internal migration.

In the 1970s, Britain reacted to what was seen as excessive non-white migration from the Commonwealth by restricting migration from all Commonwealth countries.

Man-made barriers such as dams remove water from lower sections of streams and rivers as well as restrict migration upstream.

But the likelihood is that the European leaders will decide to tighten border controls, restrict migration and discourage illegal foreign workers.

This law was exclusively concerned with restricting migration into Greece and discouraging the entrance of foreigners into Greece.

At the same time, the directive contains safety clauses worded strongly enough to restrict economic migration.

The document before us regrets, for example, that the implementation of the Schengen agreements is geared mainly to restricting migration and to maintaining law and order.