Madrid - A second deadline for Catalonia's leader Carles Puigdemont to say explicitly whether he has declared independence from Madrid or not runs out at 10 am (0800 GMT) on Thursday.
A day ahead of the deadline Spanish Prime Minister Mariano Rajoy called for a measured approach from the Catalan leadership.
"I call on Puigdemont to act in a level-headed and balanced manner and to place the interests of the citizens centre stage," Rajoy said during a parliamentary debate in Madrid.
Puigdemont said on October 10 that Catalonia had won the right to declare independence following a 90-per-cent Yes vote in the October 1 referendum, but he said he would suspend a formal declaration in order to seek dialogue with Madrid.
Rajoy rejected this and set the first deadline for Puigdemont to say clearly if he had declared independence. The deadline expired on Monday without further clarity from Barcelona.
If Puigdemont insists on pressing ahead with his plans for independence, Rajoy said Madrid would be forced to suspend Barcelona's autonomy and retake central control of Catalonia.
Article 155 of Spain's constitution would permit Madrid to sack Puigdemont and other regional office holders, dissolve the regional parliament and assume control of all regional authorities.
According to the Catalan authorities' own unverified count, 90 per cent of about 2.3 million voters backed secession. Turnout was only 43 per cent, in large part because pro-union Catalans boycotted the poll.
The vote took place despite being prohibited by the Spanish Constitutional Court.