MADRID — Anna Gabriel, a leading figure of the separatist movement in Catalonia who is due in court in Madrid this week to face possible charges of sedition and rebellion, has traveled to Switzerland, raising doubts that she will appear before the judge.

Ms. Gabriel’s party, Popular Unity Candidacy, said late Saturday that she had gone to Geneva to prepare her legal defense and bolster international support for the leaders of Catalonia’s independence movement. The argument echoed one made by Carles Puigdemont, the region’s former leader, when he fled to Belgium in October after Prime Minister Mariano Rajoy of Spain disbanded the regional government and the authorities sought Mr. Puigdemont’s arrest on sedition charges.

The party raised doubts in a statement on Saturday that she and other separatist leaders could be guaranteed a fair trial in Spain. The party said that prosecutors were seeking “very high prison sentences,” and it accused the Spanish judiciary of handling the case so far in a way far from “the impartiality that should be guaranteed by judicial authorities.”

Spanish politicians on Sunday warned Ms. Gabriel against following Mr. Puigdemont’s example. “We’re noting today that it looks as if the modus operandi of Mr. Puigdemont is spreading,” Andrea Levy, a senior member of Mr. Rajoy’s conservative Popular Party, told reporters.