Paolo Gabriele has now been held for 50 days. Federico Lombardi, a spokesman for the Vatican, said he will remain behind bars at least "for another few days," the Italian news agency ANSA reported.
About 30 people have been questioned so far, Lombardi said. "Formal interrogation of Gabriele" can begin once investigators have finished with other interviews, he added.
The Vatican has a small jail but anyone who receives a substantial sentence is transferred to an Italian prison and housed there at the Catholic church's expense.
Gabriele is suspected of leaking documents, including letters from Carlo Maria Vigano, formerly Vatican City's deputy governor and now its ambassador to the United States, to the pope and Secretary of State Tarcisio Bertone.