Spain's Constitutional Court on Thursday blocked the prosperous Catalan region's plan to vote on independence from Spain.
The ruling was expected after Prime Minister Mariano Rajoy vowed earlier in the day to "stop at nothing" to prevent the independence referendum called by the regional leaders from taking place.
According to court regulations, the suspension lasts five months while judges come up with a ruling.
The pro-independence coalition ruling Catalonia claims that the universal right to self-determination overrules Spain's laws.
The regional parliament on Wednesday approved a law to legitimize the independence vote and set an October 1 date for it.
It is not clear how such a vote might turn out. Polls in the northeastern region show support for self-rule waning as Spain's economy improves. But the majority of Catalans say they do want the opportunity to vote on whether to split from Spain.
Deputy Prime Minister Soraya Sáenz de Santamaría on Wednesday condemned the Catalan leadership for carrying out "an act of force" and for acting more like "dictatorial regimes than a democracy."
"What is happening in the Catalan parliament is embarrassing, it's shameful," she told reporters.