In a series of statements and tweets since Sunday, Esteban González Pons, a member of Spain's ruling Popular Party, also denounced Belgium's interior minister for accusing Madrid of mismanaging the secessionist crisis.
"There is no conflict between Belgium and Spain but there is an internal conflict between Belgians, between Flanders and Wallonia," he told Spanish television, referring to the Dutch-speaking northern and French-speaking southern regions.
Sacked Catalan leader Carles Puigdemont's arrival in Belgium last week has caused problems for the government led by Prime Minister Charles Michel, who rules in a coalition with Flemish separatists sympathetic to the region's independence cause.
On Sunday, Belgium's Interior Minister Jan Jambon, a member of nationalist party New Flemish Alliance (N-VA), questioned why the EU had not denounced Spain's detention of Catalan leaders.
A Spanish judge on Thursday ordered eight members of Catalonia's deposed government put into custody pending an inquiry into their push to break the region away from Spain.
Puigdemont and four sacked ministers will appear in court on November 17 as Belgium considers a Spanish request for their extradition.
"The Flemish are pro-independence and want the Catalan process to succeed," González Pons said.
He accused Jambon of belonging to a "party that collaborated with the German occupation in World War II, a xenophobic party that is an unsavoury ally for anyone."
Jambon stirred outrage in 2014 by suggesting that Flemish groups who collaborated with the Nazis "had their reasons".
Puigdemont acknowledged last week that he had gone to Belgium partly to take the Catalan issue to the heart of the European Union, which has backed Madrid during the crisis.