Accusations about Silvio Berlusconi’s historic ties to a close associate of the Sicilian mafia are being revived by his main political rival as Italy heads into the final stretch of campaigning before the general election on 4 March.

Alessandro di Battista, a top official in the Five Star Movement, asked followers on Twitter to share his scathing takedown of the former prime minister, delivered at a rally earlier this month, in which he cited a court ruling against a former longtime aide to Berlusconi and the founder of Forza Italia, Marcello Dell’Utri, who is in jail because of his ties to the Cosa Nostra.

The attack against Berlusconi’s links to organised crime reflect the battle for votes in southern Italy that is under way between his centre-right coalition and the populist Five Star Movement, which has previously won strong support in the south but appears to have lost ground to the former prime minister.

Di Battista accused Berlusconi of “making the mafia stronger” at a time in the 1990s when it was at war with the Italian state and had murdered Giovanni Falcone and Paolo Borsellino, two high-profile judges revered in Sicily.

“You must know that there are millions of Italians who struggle every day, who raise their heads and speak up, who do not forget, who say out loud that the mafia is a mountain of shit and who think that jail is the only place where Mr Berlusconi belongs,” Di Battista said.

Alessandro Di Battista launches attack against Silvio Berlusconi’s ties to the Cosa Nostra

The statement has revived an issue that has not been widely debated in the Italian election campaign.

Berlusconi has always denied having ties to organised crime. But his entry into politics was guided by Dell’Utri, a man who is now sitting in prison for being an “ambassador” to the Cosa Nostra. Dell’Utri, who was also a longtime business associate of Berlusconi, was arrested in Lebanon in 2014 as a fugitive, having fled Italy a day earlier.

If Berlusconi’s coalition – which includes two parties on the far right – were to win the election, the 81-year-old would not be eligible to serve as prime minister because of a previous conviction on tax fraud. But he would have the power to select the country’s next prime minister and would have sway over that individual given his position as head of Forza Italia.