Urban citizens benefit from the hukou system, but those who migrate between cities are also irked by it.

ECONOMIST: Migration in China

Prospects for reform of the hukou system are only slightly better.

ECONOMIST: Urbanisation

For years reformers have called for changes in the hukou system.

ECONOMIST: Problems for migrants: ��Don��t complain about things that you can��t change�� | The

One of the greatest issues for China's 250 million migrant workers is the "hukou" system of household registration.

CNN: China's workforce at a crossroads

In China's system of household registration (known as hukou), children born to rurally registered parents count as rural, even if their parents have migrated to the city, and regardless of where they themselves were born.

ECONOMIST: Problems for migrants

The system allows a person to hold only one hukou, but some find ways to bend the rules.

BBC: China media: Corruption focus