A manager at GO Lorrie’s, one of the largest passenger shuttle companies at San Francisco International Airport, solicited and reimbursed as much as $8,000 in contributions from employees to the election campaign of interim Mayor Ed Lee, employees told The Bay Citizen this week.

If so, such actions may violate the California Political Reform Act, which prohibits donors from channeling money through others to sidestep contribution limits.

Gerry Shih/The Bay Citizen

City records show that 16 GO Lorrie’s employees — including drivers, dispatchers and a clerk — gave $500 each to Lee’s campaign, the maximum allowed under city law. No other business had as many employees contribute to the mayor.

Two GO Lorrie’s drivers, Darrin Yuan and Paul Hsu, both of San Francisco, independently said in interviews that they had donated to Lee because a manager, Jason Perez, promised to reimburse them. The workers did not know whether the manager was acting on his own or on behalf of the company.

Perez, who also gave $500 to Lee, denied that any employees were solicited. He said he personally supported Lee but declined to discuss his subordinates’ contributions.

“I made the donation out of my own pocket because I think he’s the best person for the job,” Perez said.

The contributions were made in mid-September, shortly after airport officials reversed a decision to overhaul curbside parking rules that would have given the dozen shuttle companies at the airport equal opportunity to solicit exiting passengers.

Halting the overhaul benefited two companies, GO Lorrie’s and American Airporter, that had complained that the plan was hurting their revenues.

“The companies were pretty unhappy about what was transpiring,” said Alex Tourk, a lobbyist for American Airporter.

At the same meeting, on Sept. 6, airport officials also decided to begin licensing shuttle companies, which is likely to reduce vendors but benefit larger operators like GO Lorrie’s.

The campaign contributions raise yet another ethical issue for Lee, months after his political ally Rose Pak, the Chinatown lobbyist, came under criticism for pressuring a city contractor to help work on the "Run, Ed, Run" campaign that culminated in Lee’s officially entering the race.

Ann Ravel, the chairwoman of the California Fair Political Practices Commission, said the group had begun an investigation into the contributions in response to a query from The Bay Citizen.

In an interview in English and Mandarin at his home in the Richmond district this week, Yuan, 38, said Perez asked him several times over two months to support Lee.

“He said: ‘You give me $500 check. I give you $500 cash,’” said Yuan, who, like many other drivers, is a Chinese immigrant.

Yuan said he knew nothing about the mayor when Perez urged him to give: “I said: ‘Who is Ed Lee? I don’t even know him.’ And he said: ‘Look, he’s the mayor! A Chinese!’”

It remains unclear whether the donations affected shuttle policy at the airport.

Michael McCarron, an airport spokesman, said City Hall had not influenced any recent decisions at the airport. Likewise, Christine Falvey, Lee’s spokeswoman, said the mayor’s office “has not intervened” in any airport matters.

Tony Winnicker, a spokesman for Lee, said Thursday afternoon that the campaign had returned the contributions from GO Lorrie’s Thursday morning.

“We thought, ‘This is suspicious,’ and we returned them,” Winnicker said. “You have no idea the extent we go to to make sure all our contributions are above board. We have an entire compliance operation, exactly because of the scrutiny that we’re under.”

A version of this article also appears in the Bay Area edition of The New York Times.