Spain is to start suspending Catalonia's autonomy from Saturday, as the region's leader threatens to declare independence.
The government said ministers would meet to activate Article 155 of the constitution, allowing it to take over running of the region.
Catalonia's leader said the region's parliament would vote on independence if Spain continued "repression".
Catalans voted to secede in a referendum deemed illegal by Spain.
Some fear the latest moves could spark further unrest after mass demonstrations before and since the ballot on 1 October.
Article 155 of Spain's 1978 constitution, which cemented democratic rule after the death of dictator General Francisco Franco three years earlier, allows Madrid to impose direct rule in a crisis but it has never been invoked.
BBC Madrid correspondent Tom Burridge says that for Madrid this is about upholding the rule of law in Catalonia, protecting the Spanish constitution and disciplining what it sees as an unruly, disobedient devolved government.
However, the central government wants to minimise the risk of large-scale demonstrations, our correspondent says. Civil servants and government lawyers have thought long and hard about what measures to adopt and when and how they should be implemented.
