Italy's infrastructure minister has resigned following the arrest of a former top official in a corruption probe of some of the nation's major public works projects.

Minister Maurizio Lupi told Parliament Friday he decided to step down even though he is not under investigation. He denies any wrongdoing.

Four people, including the ex-ministry official who oversaw infrastructure projects under seven governments, were ordered arrested on Monday.

Prosecutors are investigating suspected corruption in connection with some of Italy's most ambitious projects, including stretches of a high-speed train line, the Italian pavilion for the world's fair that opens soon in Milan and Rome's subway expansion.

The resignation could lead to a Cabinet reshuffle. The government of Premier Matteo Renzi has been plagued by coalition bickering almost from its inception last year.