If separatist leader Carles Puigdemont does not provide a satisfactory response by 08.00 GMT on Thursday, “Mr Puigdemont will provoke the application of article 155 of the constitution,” Soraya Saenz de Santamaria told parliament.
This provision of the constitution — which has never been used before — would open the way for Madrid to impose direct rule over the semi-autonomous region.
Triggering it could represent a drastic escalation of Spain's worst political crisis in decades which was sparked when Catalonia held a banned independence referendum on October 1.
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Puigdemont declared independence following the poll which he says resulted in a 90 percent “yes” vote, though turnout was only 43 percent as many supporters of Spanish unity stayed away in a region that is deeply divided on the issue.
But the Catalan leader said he was “suspending” independence to allow time for talks with the government — a prospect Madrid has rejected, leaving the country in limbo.
Prime Minister Mariano Rajoy has given Puigdemont until Thursday to come up with a definitive answer on the independence question, or face the consequences.
“All I ask of Mr Puigdemont is that he acts with good sense,” Rajoy told parliament on Wednesday.
READ ALSO: Spain gives Puigdemont until Thursday to pull back independence push
The premier would need Senate approval to trigger article 155, but his conservative Popular Party has a majority there.
The move could ultimately allow Madrid to suspend the regional government and eventually trigger new elections for Catalonia, but such a move risks inflaming tensions in the region even further.
Jordi Xucla, a lawmaker from Catalonia's ruling coalition, told Rajoy in parliament that such a move would be “a serious mistake… its application would be difficult and questionable.”