Lt. Gov. Gavin Newsom told Bay Area business leaders Tuesday that boosting the amount San Francisco spends on homeless programs by hundreds of millions of dollars would only exacerbate the problem.

“Put another $400 million in the homeless problem and I promise you this: Your problem is going to get a lot worse,” the Democratic candidate for governor said.

Newsom later explained that he was making a pitch for a regional approach to solving problems.

“You’re not going to solve this homeless problem in San Francisco,” he said. “It’s not a San Francisco issue; it’s a regional issue.”

Speaking to reporters after his hour-long discussion with about Bay Area Council members, Newsom said he wasn’t opposed to San Francisco increasing its spending on homelessness, but that the city can’t solve the problem by itself.

The homeless population “is not static,” he said, and most of the people on the streets are not San Francisco residents. Many, he said, are not even Californians.

Asked if he thought San Francisco’s spending on programs attracted more homeless people, Newsom noted that when BART was shut down by strikes twice in 2013, the number of “panhandlers” in the city declined noticeably.

Newsom made addressing homelessness a centerpiece of his 2003 campaign for San Francisco mayor. He said Tuesday that the “Care Not Cash” program that he sponsored while on the Board of Supervisors, which substituted housing and services for monthly case payments, provided “very relevant” examples of homeless people being lured to San Francisco “because San Francisco was doing something no one else was.”

Newsom said his statement about the futility of vast increases in spending shouldn’t be seen as an indictment of those who want San Francisco to spend more fighting homelessness. Instead, he said, it demonstrated his support for a regional, or even statewide, approach.

“San Francisco needs some support,” he said, “and other cities and the state need to step up their game.”

Michael Cabanatuan is a San Francisco Chronicle staff writer. Email: mcabanatuan@sfchronicle.com Twitter: @ctuan