Cécile Kyenge, an MEP who had bananas thrown at her and was likened to an orangutan during her time as Italy’s integration minister, is being sued for defamation by the far-right interior minister, Matteo Salvini, for calling his party, the League, racist.

Kyenge will face trial in the northern city of Piacenza over comments made in an interview in 2014 during the Festa de l’Unità, a social democratic event celebrated across Italy each year. She was responding to a photograph posted on social media by Fabio Rainieri, who at the time was party secretary in the Emilia-Romagna region, depicting her as an orangutan.

On being notified of the trial on 14 September, Kyenge, who moved to Italy from the Democratic Republic of the Congo in 1983 to study medicine, wrote on Facebook: “Today in Piacenza: Salvini has summoned me to court because I said the League is racist. Judge for yourselves.”

Alongside the post were examples of headlines generated by the party over the years, including one dating back to 2009 when Salvini called for racial segregation on Milan’s public transport system.

Salvini, who became interior minister in early June, made two previous attempts to open a defamation case against Kyenge. The latest was successful because the judge ruled that her comments not only stained the party but insulted all its members.

“Now that he is a minister he is more powerful,” Kyenge told the Guardian.

Kyenge was the target of racist abuse when she was appointed as Italy’s first black minister in Enrico Letta’s government in 2013. One of the most high-profile attacks came from Roberto Calderoli, a League senator, who said at a party rally that whenever he saw pictures of Kyenge “I cannot but think of the features of an orangutan”.

Kyenge is pursuing a legal case against Calderoli and about 10 other Italian politicians over alleged racist slurs and verbal attacks. Mario Borghezio, an MEP with the League, was ordered last year to pay €50,000 (£44,000) for describing Letta’s administration as the “bongo-bongo government” upon Kyenge’s appointment.

“I said publicly several times that the League must distance itself from racism and condemn and penalise it,” Kyenge said. “They not only never did this but people convicted of racist acts are still in positions of authority. If the League doesn’t distance itself it must mean that the party shares the [racist] views.”

In an interview with the Guardian in May, she said: “I have 20 cases with my lawyer. Because I think if you want to change the climate we must have some examples and some cases.”

She added: “Italy is my country. No one can say that I am not Italian. If someone comes to protest against my policy or colour of skin, I can say to them it is not my problem, it is their problem, they must accept that people of African descent is a reality in Europe.”

Meanwhile, the African Union, which represents all 55 nations on the continent, has demanded an apology from Salvini for comparing African immigrants to slaves.

At a European conference on security and immigration in Vienna last week, Salvini said: “In Italy there’s the need to help our kids have kids, not to have new slaves to replace the children we’re not having.”

The AU commission expressed dismay at Salvini, saying: “Name-calling will not resolve the migration challenges facing Africa and Europe.” It called on him to retract his statement.

Salvini was unrepentant. “There is nothing to apologise for,” he told a press conference in Rome. “I deny [making] any equation between immigrants and slaves. On the contrary, my statements in Vienna were to defend migrants, who some want to use as slaves. If some people want to think badly [that’s up to them]. He added: “Perhaps there was a mistake in the French translation.”