Madrid had given a deadline of 10:00 a.m. Monday for an official response from the region, hoping to receive a clearer indication on whether it had declared independence.
However a letter from Catalan leader Carles Puigdemont at 8.00 am failed to offer any confirmation.
Spain’s Deputy Prime Minister Soraya Sáenz de Santamaría said he had not made his position clear and that Madrid would give him until Thursday morning to give a formal confirmation.
“It’s not a hard question we have asked, it’s not a hard question to respond to,” she said.
“10:00 a.m. (local time) on Thursday is the deadline,” she added. “We are very disappointed he hasn’t given a yes or no answer to the question we asked.”
“He is prolonging the situation,” she said.
Rajoy is expected to publish a response to Puigdemont’s letter today.
The letter from Catalonia this morning only supported the offer by Puigdemont to meet Rajoy to discuss the situation, and asked that dialogue take place over the next couple of months.
Rajoy has said he would be ready to invoke Article 155 of the Spanish Constitution if a declaration of independence is announced on Thursday.
The so-called nuclear option would allow him to fire the regional government and call for fresh elections.
The chances of this happening are still relatively high, according to analysts.
“If the Catalan government chooses a hard line, we expect that Article 155 will be triggered. While it is difficult to predict the exact contours of its implementation, we foresee that in due time a new regional election will be called in an attempt to restore the normal institutional set up,” JPMorgan economist Marco Protopapa said last week.