Swedish activist Greta Thunberg attended a climate change and pro-Palestinian rally in Milan on Friday, days after her criticism of Israel sparked a row over protests in Germany.

More than 1,000 people, many of them teenagers, joined a peaceful march in the northern Italian city organised by Fridays For Future, the climate change movement Thunberg helped found.

Wearing a keffiyeh, a traditional scarf symbolising the Palestinian struggle against Israel, Thunberg walked near the front of the procession as other protesters waved flags, held banners and danced to music.

"Palestinians have been living under suffocating oppression for decades by an apartheid regime, and during the last year with Israel's live broadcasted genocide, the world has once again abandoned Palestine," the 21-year-old said in a speech.

Israel's retaliatory military offensive in Gaza has killed more than 42,000 people, most of them civilians, according to figures provided by the Hamas-run territory's health ministry. The United Nations has acknowledged the figures to be reliable.

Thunberg drew a link between global warming and the weapons industry.

"The fight for climate justice is a fight against the fossil fuel industry, just as much as it is a fight against the weapon industries, militarisation and the over-extraction of natural resources," she said.

German police on Tuesday closed a pro-Palestinian protest camp that had invited Thunberg after a rally she attended in Berlin Monday -- the anniversary of the Hamas attack -- ended in clashes with police.

She accused Germany of "silencing and threatening activists".

The Milan march was part of a "national strike for the climate", a series of protests organised by Fridays For Future across Italy.

"Demonstrating is the only weapon we have against the injustice that we suffer," said protester Sofia Parisi, 17. (AFP)