Huge numbers turned out at pro-Palestinian rallies in Europe on Saturday, calling for an immediate end to the war in Gaza and the release of activists on board a flotilla carrying humanitarian aid to the territory.

Organisers of the protest in Rome said hundreds of thousands of people had turned out for a fourth day running, after Israel intercepted the 45-strong flotilla seeking to reach Gaza earlier this week.

Some 70,000 people, according to police, took to the streets in Barcelona, in one of several pro-Palestinian protests to take place across Spain.

Elsewhere, several thousand people marched through the centre of the Irish capital, Dublin, to mark what organisers said was "two years of genocide" in Gaza.

With Ireland, Spain is one of the fiercest European critics of Israel's military offensive in Gaza, which was sparked by Hamas' October 7, 2023, attack on Israeli communities near the Gaza Strip.

But in Italy, Prime Minister Giorgia Meloni's hard-right government has been criticised for its inaction on the siege of the Palestinian territory.

On Saturday, Meloni accused demonstrators of defacing a statue of Pope John Paul II with graffiti in front of Rome's main train station, calling it a "shameful act".

"They claim to take to the streets for peace, but they insult the memory of a man who was a true defender and builder of peace," she said in a statement.

Protesters in the Italian capital, including families with children, shouted: "We are all Palestinians", "Free Palestine" and "Stop the genocide", with many carrying Palestinian flags and wearing black-and-white chequered keffiyehs.

"Usually, I don't appreciate large-scale demonstrations, but today, I couldn't bring myself to stay home," said Donato Colucci, a 44-year-old scout leader accompanying 150 youths from a secular association.

"I think countries like Italy, France, and Spain have developed a culture of resistance and democratic values more than others because they experienced dictatorship and violence."

In Barcelona, Marta Carranza, a 65-year-old pensioner demonstrating with a Palestinian flag on her back, said Israel's policy "has been wrong for many years and we have to take to the streets." (AFP)