Catalan authorities must drop a bid for independence by Thursday, the Spanish government says, as it moves closer to imposing direct rule over the region after its leader missed an initial deadline to back down.
In a confrontation viewed with a mounting sense of unease in European capitals and markets, Carles Puigdemont failed on Monday to respond to an ultimatum from Madrid to clarify if he had declared independence.
Plunging Spain into its worst political crisis since an attempted military coup in 1981, Catalan voters backed a breakaway in a referendum on October 1 that Spain's Constitutional Court said was illegal.
On that basis, Puigdemont made a symbolic declaration of independence last Tuesday, but immediately suspended it and called for negotiations with Madrid on the region's future.
Madrid had given him until 10 am (7 pm AEDT) on Monday to clarify his position on independence with a "Yes" or "No", and until Thursday to change his mind if he insisted on a split - saying it would suspend Catalonia's autonomy if he chose secession.
Deputy Prime Minister Soraya Saenz de Santamaria said after the deadline passed that he had not answered the question and had to do so by Thursday.
"Mr Puigdemont still has the opportunity to start resolving this situation, he must answer 'yes' or 'no' to the declaration," Saenz de Santamaria said.
In a letter to Spanish Prime Minister Mariano Rajoy made public on Monday, Puigdemont did not directly answer on the independence issue, instead making a "sincere and honest" offer for dialogue between the two men over the next two months. .
