BARCELONA, Spain (Reuters) - Spain warned Catalonia’s separatist government against empowering a new Catalan tax agency as part of its plan for an independent state, saying it could lead to sanctions and criminal proceedings for companies.

Catalan regional head Carles Puigdemont said on Monday the new tax agency was ready to assume responsibilities for collecting revenues previously collected by the Spanish state, such as personal and company taxes and debt payments.

Pro-separatist Catalan parties were going ahead this week with legal preparations for a disputed referendum on secession in October. Prime Minister Mariano Rajoy’s conservative government says it will strike down any such secessionist challenges in court.

Catalonia, as with other Spanish regions, already has its own regional tax agency which oversees taxes on wealth and inheritance, as well as special taxes on gambling and transportation.

But the central government’s budget ministry said on Monday that the new tax agency, with its broader planned responsibilities, could not act in place of national tax authorities.

If the national tax agency did not receive personal and company taxes it would consider that they had not been paid, the ministry said in a statement. As a result, the national tax agency could begin proceedings to ensure payment, such as by imposing sanctions.

Individuals and companies have a legal obligation to pay their taxes through the correct agency or they could be committing a crime against Spanish tax authorities, the ministry said.

Puigdemont, the regional head, said on Monday Catalonia would remain committed to “economic collaboration” with the rest of Spain after a possible declaration of independence and hoped to agree a financing deal with the central government.

“Independence is not decided by pressing a button but via a transition which we want to be done with maximum dialogue and with a possible agreement on financing,” Puigdemont told reporters.

“Today we have presented the Catalan tax agency, but we are committed to economic collaboration with the whole of Spain. We will not turn our back on Spain,” he said.

Last week, Puigdemont and other party leaders outlined the legal framework for the transition to an independent republic they say would take effect if a majority of people in Catalonia vote “yes” to splitting from Spain.