The claims have fanned a bitter debate about the nation's democratic credentials.
Catalan leaders liken the tactics of Spain's conservative Prime Minister Mariano Rajoy to those of Franco, who suppressed the region's language and culture during a rule that ended with his death in 1975.
Separatists say the crackdown on an independence vote held on October 1st prove the government would stop at nothing to prevent a "democratic" referendum.
But though deposed president Carles Puigdemont has said Spain's treatment of Catalonia exposes "serious democratic shortcomings", the separatists have been accused of making the Franco comparison in bad faith.
"What has emerged in Catalonia, this idea that in Spain 'we live under Francoism', is completely absurd," said historian Julian Casanova.
"The flaws of our democracy are ours alone."
Who's afraid of democracy?
After the regional parliament unilaterally declared Catalonia independent on October 27th, Madrid dismissed the Catalan government, suspended the region's autonomy and dissolved its parliament.
Puigdemont and other Catalan leaders fled to Belgium.
"You are Francoists, you are afraid of democracy," one of Puigdemont's former ministers, Toni Comin, said at a rally in Brussels, in remarks aimed at Spain's leaders.
Pro-independence figures hope to regain power in regional elections on December 21st. But they are under investigation for sedition, rebellion and misuse of public funds over their independence drive.
Of those still in Spain, several have been remanded in custody.
Their supporters have held several huge rallies in recent weeks, chanting slogans demanding freedom for what they call "political prisoners".
Such action against political leaders has fanned claims by separatists that Catalans are being oppressed as they were under Franco.
Franco's regime executed at least 50,000 people in the decade that followed Spain's 1936-1939 civil war.
Prominent Catalan author Eduardo Mendoza argues in his book, "What is happening in Catalonia?", that Franco's legacy is being "instrumentalised" in Spain.
That is the case "especially in Catalonia where Franco's image is paraded to justify one's conduct or invalidate that of one's adversary", he wrote.
Franco led an army rebellion against a democratically-elected republican government in 1936, triggering Spain's civil war. His side won the conflict with Hitler and Mussolini's help.
After Franco's death, Spain passed an amnesty law to smooth the transition from dictatorship to democracy, pardoning crimes of the regime.
Some of Franco's ministers then founded the Popular Alliance, the precursor to Rajoy's Popular Party.
'Guardian' of Franco's tomb?
Puigdemont regularly promises Catalans a new country "without the vices inherited from Francoism".
He has called Rajoy the "guardian" of Franco's tomb -- a reference to the government's refusal to remove the dictator's remains from a vast mausoleum near Madrid.
The allegations have touched a raw nerve in a country where many see the transition from dictatorship as a notable political achievement.
"Spanish democracy is not worse than others," Casanova said. "But it still has a lot of problems facing up to the past."
"The memory of the victims (of the Franco regime) has been trampled upon countless times."
'Unthinkable in Germany'
Franco's lingering influence is visible, however.
In April, mourners raised their arms in a fascist salute as one of the last ministers to serve under Franco, Jose Utrera Molina, was buried in Nerja in southern Spain.
Molina's son-in-law Alberto Ruiz Gallardon, a former justice minister under Rajoy and a former Madrid mayor, was among the pallbearers.
Some 230,000 people signed a petition filed in parliament in November asking the government to ban the National Francisco Franco Foundation, which glorifies the dictator.
"In Germany or in Italy, it would be unthinkable to have a Hitler foundation or a Mussolini foundation," read the petition, filed by a group that included descendants of victims of the regime.
Rajoy in 2015 bragged in public that his government had provided "zero euros" to help apply the so-called Historical Memory Law, passed by his Socialist predecessor in 2007.
Its provisions included the removal of Francoist symbols from public places and state help in locating and exhuming the tens of thousands of bodies of victims of his repression who still remain missing.
Philosopher Manuel Reyes Mate says that, though there are still "vestiges" of Franco's regime, supporters of the independence drive must not make the mistake of imposing their will on fellow Catalans who do not want to secede.
Secessionists, he says, "use rhetorically the idea that the state is Francoist -- but meanwhile they propose a new identity, a new country, against the will of half of Catalans."
By Laurence Boutreux / AFP