5-Star leader and Italian Deputy Prime Minister Luigi di Maio presents his EU election program in Rome, Italy, May 2, 2019.
5-Star leader and Italian Deputy Prime Minister Luigi di Maio presents his EU election program in Rome, Italy, May 2, 2019.

ROME - Italy's anti-establishment 5-Star Movement piled pressure on its government partner the League on Sunday to dump a junior minister under investigation for corruption, in a case that could pull the coalition apart.

Relations between 5-Star and the far-right League have grown increasingly fraught in the run-up to European Union parliamentary elections on May 26, with the two parties acting more like bitter political enemies than cabinet allies.

Their growing rivalry triggered an unprecedented spat between the interior and defense ministries at the weekend as tensions grew over the fate of junior transport minister Armando Siri, who is very close to League leader Matteo Salvini.

Siri last month was put under investigation for allegedly accepting a bribe from a wind farm entrepreneur who has been linked to the Sicilian Mafia. Siri has denied wrongdoing, but 5-Star has said he must resign for the good of the government.

Prime Minister Giuseppe Conte, who belongs to no party and presents himself as the mediator between the two cabinet partners, agreed last week that Siri must go.

However, the League, which has surged in the polls over the past year and has easily overtaken 5-Star as Italy's leading party, has so far refused to back down, saying he has not been charged and not yet had a chance to speak to investigators.

5-Star leader Luigi Di Maio urged Salvini on Sunday to tell Siri to go before the cabinet meets on Wednesday to discuss the issue and hold a possible vote on his dismissal. 5-Star has more ministers than the League, so should win any such ballot.

While he said his party would not abandon the coalition even if League ministers sought to protect Siri in a vote, Di Maio said ramping up tensions between the two parties risked taking it to the point of a breakdown.

"I don't think the League wants things to get to a vote and to a rupture," Di Maio told Rai television.

Matteo Salvini, Italy's Deputy Prime Minister and
Matteo Salvini, Italy's Deputy Prime Minister and leader of the far-right League Party, speaks to the media after launching the start of his campaign for the European elections, in Milan, Italy, April 8, 2019.

"What I say to Salvini is, that it's all very well being tough with the weak, but now is the moment to show some courage," he said.

However, during a weekend of increasingly harsh exchanges, there was no sign of a League retreat.

"I am not used to abandoning people who have worked alongside me," Salvini, who serves as interior minister, told a political rally on Saturday.

In an effort to shift the focus from Siri, the interior ministry launched a broadside against 5-Star Defense Minister Elisabetta Trenta after her office wrongly tweeted that the navy had thwarted an attack on an Italian fishing boat.

The erroneous tweet was swiftly deleted, but the interior ministry accused Trenta's staff of spreading false news.

"The defense minister should act like a defense minister.

The Armed Forces deserve much better," a statement said.

5-Star said Salvini had "crossed a red line" by using his ministry to attack another for electoral purposes.

Several Italian newspapers quoted sources within the League at the weekend as saying they were fed up of working with 5-Star, and predicting the government would fall after the May 26 vote.

Salvini denied the reports and accused journalists of generating "pointless" controversies. "The government will last for four years," he said on Saturday.