A top public works official in Argentina's previous government was arrested on Tuesday while throwing what police called "an obscene amount of cash" over the walls of a monastery, intensifying questions about possible past corruption.

Officers responded to a pre-dawn 911 call reporting a man tossing bag after bag into the Our Lady of Fatima Catholic monastery in the Buenos Aires suburb of General Rodriguez.

Within minutes, officials said, former Deputy Public Works Minister Jose Lopez was in custody, where he remained on suspicion of money laundering.

"He has to explain," Cabinet chief Marcos Pena told reporters. "Lopez managed everything that had to do with public works under the previous government. This confirms there were enormous problems with transparency, at least, and at most, serious corruption."

Lopez at one point told nuns at the scene that he had planned to donate the cash to the monastery, officials said.

Reuters was unable to contact his lawyers.

The case is the latest to focus on figures linked to Cristina Fernandez, whose second term as president ended in December. Prosecutors have questioned Fernandez as part of a probe into possible corruption in her administration. She was succeeded by former Buenos Aires Mayor Mauricio Macri.

Local media reported that $8 million to $10 million worth of various currencies was recovered. But as of late Tuesday afternoon, Buenos Aires provincial security chief Cristian Ritondo said the money was still being counted.

"We found an obscene amount of cash at the convent, where neighbors and even the nuns living there told us that a lot of officials from the previous government had visited," he said.

"It was in four different currencies. Most of it was in dollars. The rest was in euros, yen and a currency from Qatar, of which we are still not sure of the value," he added.

"He was caught red-handed," Ritondo said, adding Lopez had a rifle with him when he was arrested. "He tried to bribe one of the officers, and the bribe was rejected."

Officers confiscated six upper-end wrist watches from Lopez, brands including Rolex, Omega and Tommy Hilfiger.

Asked by a reporter what kind of condition Lopez was in, Ritondo said: "He's depressed."

(Reporting by Hugh Bronstein; Editing by Peter Cooney)