Facebook and Instagram have closed the official accounts of the Italian neo-fascist party CasaPound and the profiles of dozens of far-right activists.

The party had almost 240,000 followers on Facebook. “This is an unprecedented attack. We are disgusted,” said CasaPound’s president, Gianluca Iannone. “We will file an urgent class-action lawsuit against an act of disgraceful prevarication.”

A Facebook spokesman told the Italian news agency Ansa: “Persons or organisations that spread hatred or attack others on the basis of who they are will not have a place on Facebook and Instagram. The accounts we removed today violate this policy and will no longer be present on Facebook or Instagram.”

It is not the first time Facebook has taken action against CasaPound. Last April, activists from CasaPound as well as other far-right Italian politicians, including the great-grandson of Benito Mussolini, accused Facebook of discrimination after their accounts were suspended.

CasaPound was founded in the late 1990s as a pro-Mussolini drinking club. Named after the 20th-century American poet Ezra Pound, who was known for his fascist sympathies and antisemitism, it claims to support a democratic variant of fascism but it is accused of encouraging violence and racism.

In a 2011 interview with the Guardian, the party’s secretary, Simone Di Stefano, described Mussolini’s brand of fascism as “our point of reference, a vision of the state and the economy, and the concept of sacrifice”. Di Stefano ran for prime minister in the last general election.

On Monday, CasaPound members took part in a demonstration in Rome against the new Italian government, an alliance between the centre-left Democratic party and the anti-establishment Five Star Movement. Some protesters gave fascist salutes and chanted choruses praising Mussolini.