The member of the far-right PNR National Renovator Party had to be subdued and handcuffed by police after disrespecting police orders and repeatedly trying to perforate a police barrier that separated the opposing sides.
He was taken to a police station, formally identified and later released.
Tensions sparked between the two demonstrations in Martim Moniz.
Thousands of immigrants took to Lisbon’s streets yesterday to demand solutions to the situations of some 30,000 immigrants who live, work and pay taxes in Portugal but don’t have a residence permit.
The PNR was protesting against an “invasion of immigrants” and “for social justice for Portuguese.”
On Sunday evening, PNR members moved to gather by the Free Party’s headquarters, where a public debate on ‘How to fight Trumpism – notes and lessons on the US Campaign’ was due to take place.
A PSP police source told Lusa News Agency that that action had passed without incident.