Carles Puigdemont, president of the Catalan regional government | Lluis Gene/AFP via Getty Images Catalan separatists resume secession push after terror truce Parties present bill setting out first steps as independent country.

MADRID — Catalan pro-independence parties on Monday resumed their push for secession, breaking a tense truce that went into place following this month's terror attacks in Barcelona and Cambrils.

The separatist alliance of three main parties from the center-right to the radical left, which holds an absolute majority in the regional parliament, outlined legislative plans for an independent Catalonia sure to anger the government in Madrid.

The proposed bill sketches out what the first days of life as an sovereign country would look like if Catalans vote for secession in a referendum the regional government plans to hold on October 1. Spanish Prime Minister Mariano Rajoy has vowed to prevent the vote by all legal means necessary.

The bill says it will be the supreme law of a new Catalan republic pending the approval of a constitution. It stipulates that the regional president — currently Carles Puigdemont — will be the new head of state and the regional chamber the new parliament. The text deals as well with issues like nationality, the judiciary and electoral bodies.

The bill follows the proposal in July of a self-determination referendum law. Both bills are meant to set out the legal foundations for Catalonia to secede from Spain. Neither has been passed by the regional chamber.

Their approval in the coming weeks would trigger judicial hostilities with the country’s Constitutional Court, which is expected to overturn both laws.

Next steps unclear

What happens next is still a matter of speculation, but Puigdemont has repeatedly made clear his willingness to go ahead with the vote and the secession of Catalonia. That could plunge Spain into a constitutional crisis, with a regional government in open rebellion against Madrid.

The terrorist attacks two weeks ago that killed 16 people brought only a brief spell of unity. Even before the bill was unveiled, Spanish security forces and the regional police of Catalonia had traded accusations over the lack of cooperation and exchange of information.

Hundreds of people booed King Felipe VI and Spanish officials in a demonstration against terror in Barcelona on Saturday. Puigdemont accused the Spanish government of “playing politics” with the security of Catalans in an interview with the Financial Times.

Rajoy on Sunday defended “unity” as the only way to defeat terror and demanded that Catalan separatists abort their “plans of rupture, division and radicalism,” while warning that Madrid will defend national sovereignty, the constitution and the rule of law.

The leader of Spain’s main opposition Socialists, Pedro Sánchez, talked to Rajoy on Monday on the phone about the Catalan crisis and both leaders committed to cooperate on “a joint position” to respond to the Catalan challenge, Socialist spokesman Óscar Puente told reporters. Puente added Rajoy was “moving clearly in the terrain of proportionality and seeking the most efficient way” to tackle the crisis.