The march, which has often been marred by violence by far-right groups in the past, went ahead on Wednesday despite an official ban on gatherings due to the coronavirus epidemic.
Rioters pelted police with fireworks and stones, and also attacked shops and homes. The police responded with pepper spray, rubber bullets and stun grenades.
Sylwester Marczak, spokesman for the Warsaw police, said that 35 officers were injured, and that some were still in hospital.
“Some of the officers have had back injuries, other head injuries, and one has a broken arm,” Marczak added. “Three are still in hospital. This shows the kind of attitude some of people who participated in the events had.
“We had over 40 incidents of a criminal nature, and that 36 people have been arrested,” he continued.
One photo journalist was also shot in the face with a rubber bullet. A number of other journalists near the National Stadium complained of being attacked with stun grenades and of being beaten by the police despite identifying themselves as members of the press.
Michal Dworczyk, the head of the prime minister’s office, said that "in such situations police are obliged to act" and that "any controversies must be very thoroughly investigated."
He also accused Warsaw Mayor Rafal Trzaskowski, who criticised the march and said the ruling party was responsible for inciting nationalist sentiments, of using the unrest for political ends.
During the demonstrations, ambulance access to the makeshift COVID-19 hospital at the National Stadium was blocked.
A Warsaw City Hall spokesperson said demonstrators had damaged the city’s road infrastructure by ripping up paving stones and posts. (PAP)