MADRID — Carles Puigdemont, the former leader of Catalonia wanted in Spain on rebellion charges, was detained on Sunday in Germany on an international arrest warrant, in a move that drags Berlin into Spain’s festering territorial dispute.

Mr. Puigdemont was arrested by a German highway police patrol soon after crossing the border with Denmark. He was traveling by car to Belgium from Finland, and had planned to present himself to the Belgian authorities, according to Mr. Puigdemont’s lawyer, Jaume Alonso-Cuevillas.

The arrest came two days after Spain, trying to strike a decisive blow against the secession movement, reactivated a European arrest warrant against Mr. Puigdemont and five other separatist leaders.

Catalonia has been in political turmoil since its leaders formally declared independence in October and the central government ousted them, assuming direct control of the wealthy autonomous region. Madrid also moved to prosecute Mr. Puigdemont and his allies for rebellion and sedition, prompting some to flee to several other European countries.