Jorge Fernandez Diaz, the Spanish interior minister announced in Congress on Wednesday that a reform of the penal code was planned to criminalise those involved in organising street protests that "seriously disturb the public peace".
Under the laws, a minimum jail term of two years could be imposed on those found guilty of instigating and carrying out violent acts of protest under a new package of measures unveiled on Wednesday.
But it has raised fears that the new measures could be used to stem the wave of protests that began last summer with the birth of what has been dubbed the "indignado movement", when tens ouf thousands of peaceful protesters camped out in squares across Spain.
Protest groups were quick to draw comparisons to the fascist dictatorship of Gen Grancisco Franco.
The measures come amid growing incidents of street violence in cities across Spain, most notably Barcelona where "anti-capitalist" groups were blamed for stirring tensions during last month's general strike.