(Bloomberg) -- Deputy Premier Matteo Salvini's top aide turned against Prime Minister Giuseppe Conte as tensions within the populist government escalated over immigration before this week’s European vote.

Giancarlo Giorgetti, who's also Cabinet secretary, voiced long-running frustration among lieutenants of the right-wing League party against the anti-establishment Five Star Movement, which picked Conte a year ago.

“Conte is no longer impartial,” Giorgetti told newspaper La Stampa. Conte tries to act as a mediator between the League and Five Star but “when the clash becomes tough and he has to take a side, he goes for the stand of those who put him forward,” Giorgetti said. “The situation cannot last for ever.”

Conte, a former law professor, was plucked from obscurity by Salvini and fellow-Deputy Premier Luigi Di Maio last year. While never a member of Five Star, Conte was loosely affiliated with the movement in the past and Di Maio once named him as a possible candidate to head the Public Administration Ministry.

Both Salvini and Di Maio have repeatedly insisted the government won’t collapse despite unprecedented tensions before the European Parliament elections on May 26. The partners have squabbled about issues from security and immigration to more powers for regions in the League’s northern stronghold.

Coalition Infighting

Quarreling between the League and Five Star, including over Salvini’s threat last week to challenge European Union limits on budget deficits and public debt, has spooked financial markets, widening the yield spread between Italian and German government bonds last week.

Senior officials in both the League and Five Star have said the infighting is mainly due to the election campaign, although uncertainty remains on the coalition’s future.

Salvini, who is also interior minister and has insisted Italian ports must remain closed to humanitarian ships carrying rescued migrants, protested during a live interview with television network La7 television Sunday night as he watched migrants disembark from the Sea Watch 3 vessel in the Sicilian port of Lampedusa. The migrants had been rescued off the Libyan coast last week.

“Someone must have given the order,” Salvini said as Five Star officials insisted no minister of that party had granted access to the ports. “That person has to account for his action.”

Salvini insisted that he would bring measures to give his interior ministry powers over migrant boats in territorial waters to a cabinet meeting later today and vowed to impose fines on humanitarian groups which don’t respect official orders.

To contact the reporter on this story: John Follain in Rome at jfollain2@bloomberg.net

To contact the editors responsible for this story: Ben Sills at bsills@bloomberg.net, Dan Liefgreen, Jerrold Colten

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