Spain's state prosecutor said on Monday that he would seek charges of rebellion, sedition and embezzlement against members of Catalonia's ousted secessionist government, pushing the crisis over the region's independence declaration into an uncertain new phase.

Chief prosecutor Jose Manuel Maza said he would ask judges for preventive measures against the politicians and the governing body of the Catalan parliament that allowed a vote to declare independence last week. He didn't specify if those would include their immediate arrest and detention before trial.

The rebellion, sedition and embezzlement charges carry maximum sentences of 30, 15 and six years in prison, respectively. It wasn't immediately clear when judges would rule on the prosecutors' request.

Maza didn't name any of those facing charges, but they include regional leader Carles Puigdemont, his right-arm man Oriol Junqueras and Catalan parliamentary speaker Carme Forcadell.

The announcement came as Catalonia's civil servants returned to work for the first time since Spain dismissed the separatist regional government and imposed direct control.

Speculation raged about the whereabouts of Puigdemont, as Catalans watched and wondered whether the ousted leaders would defy their firing and face even more possible criminal charges.

In addition to the sedition charges, Spain's government has said the fired leaders could be charged with usurping others' functions if they attempt to carry on working.

As staff arrived at the headquarters of the Catalan government in Barcelona, Puigdemont posted a photo on Instagram of a courtyard at the building. Both the Catalan and Spanish national flags waved from the top of the building.

The ambiguous Instagram post, accompanied by the words “Good morning” in Catalan and a smiley emoticon, left many guessing whether Puigdemont was inside the building. There was no indication of when the photo was taken.

As dozens of journalists, curious onlookers and bemused tourists gathered in the square outside the Gothic government palace in central Barcelona, residents expressed confusion about who was actually in charge of Catalonia.

“I don't know the Catalan government says they are in charge, but the Spanish government says they are,” said Cristina Guillen, an employee in a nearby bag shop. “So I have no idea, really. What I really think is that nobody is in charge right now,” she said.

At least one portrait of Puigdemont was still hanging on a wall inside the Catalan government's Generalitat building.

At least one member of the ousted government defied his dismissal by showing up at work and posting a photo on Twitter from his formal office.

“In the office, exercising the responsibilities entrusted to us by the people of Catalonia,” said Josep Rull, who until last week was the region's top official in charge of territorial affairs.

Two police officers entered and left the building, followed minutes later by Rull, who told reporters and supporters that he would continue carrying out his agenda.

But there were no official events listed on the regional government's public agenda that is published online daily.

Meanwhile, the two separatist parties in the former Catalan governing coalition held separate meetings to decide their next move.

Spanish authorities say deposed officials will be allowed to take their personal belongings from official buildings, but are barred from performing any official duties.

Interior Minister Juan Ignacio Zoido said on Monday that the government was giving the separatist politicians “a few hours” of time because the goal was “to recover normality in a discreet way and under the principle of minimal intervention” from central authorities.

Catalonia's regional parliament proclaimed independence from Spain in a secret ballot on Friday. The Spanish government dissolved the legislature, fired the government and regional police chief and called a new election for December 21.

Spanish Foreign Minister Alfonso Dastis said on Sunday that Puigdemont would be eligible to run in the election, provided he is not imprisoned.

“I don't know what kind of judicial activity will happen between now and December 21. If he is not put in jail at that time I think he is not ineligible,” Dastis told The Associated Press, speaking before prosecutors announced they were seeking charges.

The vote to secede came after an October 1 referendum in favour of independence that was deemed illegal by Spain's constitutional court.

Puigdemont has vowed peaceful and “democratic opposition” to his Cabinet's dismissal, but he hasn't clarified if that means accepting an early regional election as a way out of the deadlock.

Separatist parties and grassroots groups have spoken of waging a campaign of disobedience to hamper the efforts by central authorities to run the region.

A key factor will be how Catalonia's estimated 200,000 public workers react to their bosses' dismissal, and whether any stay away from work in protest.

Secession moves by this wealthy northeastern region of 7.5 million have tipped Spain into its deepest crisis in decades.

On Sunday, hundreds of thousands took part in an anti-independence demonstration in Barcelona, calling for Catalonia to remain in Spain and backing Rajoy's use of unprecedented constitutional powers to seize wrest control from the pro-independence regional administration.

“We won't let Spain be torn apart into pieces,” read one banner. “The awakening of a silenced nation,” read another.

“We have organised ourselves late, but we are here to show that there is a majority of Catalans that are no longer silent and that no longer want to be silenced,” said Alex Ramos, head of Catalan Civil Society, a pro-union grassroots group.

The organisers said more than one million people turned out but police put the figure at 300,000.

Many who oppose independence fear the political turmoil in Catalonia could have a severe economic impact, both in the region and on Spain as a whole.

Some 1,700 companies have already relocated their headquarters to other parts of Spain in recent weeks amid the uncertainty.

Spanish financial markets rose on Monday after a poll suggested more Catalans oppose the declaration of independence than support it. The Ibex 35 stock index was up 1.4 per cent at 10,338 points, about as much as it had fallen on Friday. Spanish government bonds were also higher.