Spain's chief public prosecutor on Monday refused to rule out ordering the arrest of Catalonia's president as Spanish authorities continued a crackdown against a banned independence referendum in the region.

Jose Manuel Maza said Carles Puigdemont could be charged with civil disobedience, abuse of office and misuse of public funds for pressing ahead with preparations for the October 1 referendum.

"It's a decision that is possible but we have not considered that we should take it," Maza said during an interview with Onda Cero radio.

Prime Minister Mariano Rajoy, who meets US President Donald Trump in Washington on Tuesday, has repeatedly said that the vote - which his conservative party insists is illegal and unconstitutional - will not take place.

The legislation underpinning the vote has already been suspended by Spain's Constitutional Court.