Updated

Thousands of pro-Catalan independence supporters have protested the start of a Spanish court investigation into the regional government's staging of a symbolic referendum on secession from Spain last year.

New Barcelona mayor Ada Colau headed the protest Tuesday and read a statement backing Catalonia's demand for the right to self-determination. The rally came after a regional official and a former regional deputy president appeared for questioning over their suspected roles in holding the poll.

Regional acting President Artur Mas is also under investigation and is scheduled to testify Thursday.

Spain's Constitutional Court suspended the Nov. 9, 2014, referendum but Catalonia held it anyway, calling it an informal effort. About 2.3 million Catalans — out of 5.4 million eligible — voted, with 80 percent in favor of breaking away from Spain.