Catalonia's ousted leader Carles Puigdemont and four former ministers turned themselves in Sunday in Brussels, following Spain's issuance of a warrant for their arrests.
Puigdemont had said Saturday he intended to cooperate with officials in Brussels, where he fled last week, tweeting, "We are prepared to fully cooperate with Belgian justice following the European arrest warrant issued by Spain."
A Spanish judge issued the warrant for Puigdemont a day after she jailed nine members of the region's separatist government pending possible charges over last week's declaration of independence. One person was later granted bail.
The National Court judge filed the request with the Belgian prosecutor to detain Puigdemont and his four aides, and issued separate European search and arrest warrants to alert Interpol in case they fled Belgium.
Belgian federal prosecutors said they had received the arrest warrant and could question Puigdemont in coming days.
Puigdemont and the four others were being sought on charges that included rebellion, sedition and embezzlement as a result of a Spanish investigation into their roles in pushing for secession for Catalonia.