ROME -- Police arrested two more suspects Thursday in Rome's widening corruption and mafia scandal as the Italian government prepared to announce new measures to punish such crimes.

The two suspects are accused of helping bring members of the 'ndrangheta mob into what prosecutors have said was a well-oiled system in the Italian capital to win public contracts. The contracts involved servicing refugee centres, Roma camps and other operations. Nearly 40 people have been arrested and a former mayor is under investigation in the probe.

The latest arrests concerned a contract to clean a central Roman market, police said.

Premier Matteo Renzi has called a Cabinet meeting Friday to approve new measures that reportedly include extending the statute of limitations and prison terms for corruption.

"Of the 50,000 people in prison, only 257 are there for corruption," Renzi tweeted Thursday. "That's not serious. Indignation isn't enough: As of tomorrow's Cabinet meeting, tougher rules."

Phone conversations intercepted by police and published in the media over the past week have described how local criminal bosses managed to cement ties with city politicians over lucrative public contracts.

The unfolding drama is the latest corruption scandal to hit Italy after a series of arrests earlier this year involving two major public works projects: Milan's Expo 2015 world's fair and Venice's Moses project to build sea barriers to protect the lagoon city from flooding.

On Thursday, Renzi's anti-corruption czar, who was named in the wake of the Expo and Moses scandals, said even he was shocked by the depth of corruption in Rome.

"I never imagined such a profoundly gangrene system in some offices," Raffaele Cantone said.