(06-09) 07:47 PDT OAKLAND -- A minor traffic collision involving Oakland Mayor Jean Quan on Sunday could blossom into a major political liability if the claims of the other driver are verified - that Quan ran a red light while talking on her mobile phone.

Oakland police spokesman Officer Frank Bonifacio confirmed that Quan was one of the drivers involved in the crash at 5:39 p.m. at 26th and Market streets in West Oakland, but he said the department's traffic division will have to investigate the circumstances.

Quan, who is in a tough fight for re-election in the fall, was not hurt in the collision.

But the driver of the other car, a Nissan, told reporters she could see Quan on the phone at the time of the crash and that the mayor had run a red light.

"I think she's being very irresponsible," said Lakisha Renee Lovely, adding that Quan was "behaving badly" because she was on the phone. "That shows she's not responsible."

'I was not on my phone'

But Sean Maher, Quan's director of communications, was unequivocal. The mayor, he said, "was absolutely not on the phone."

"We are going to be requesting her phone records from the phone company" to give them to investigators, Maher said. "Those records will support that the mayor was not on her phone."

For her part, Quan posted messages on Facebook and Twitter late Sunday, saying she would let police "do their job." But she also said the investigation "will confirm that I was not on my phone at the time!"

"Thanks to all who have sent messages of concern," she wrote. "This evening I was driving between two community events in West Oakland when another vehicle struck my left-rear tire. I immediately pulled over and checked to make sure no one was hurt: it appeared everyone was all right and their well-being was my first priority. ... I'm grateful that no one has been reported injured."

An occupant of the Nissan complained of pain as a result of the crash, authorities said. Paramedics were called to the scene, but no one was taken to a hospital, Bonifacio said.

Maher said Quan was driving her city-owned Lexus sport utility vehicle from one church meeting to another when the collision occurred in the intersection. Maher said he believes Quan was driving on Market Street when the other car hit the SUV's left rear tire.

Rocky road to re-election

Depending on the outcome of the police investigation, the collision could add yet another speed bump to Quan's road to re-election in November.

Her first term as mayor has been marked by numerous challenges, including a Police Department that came under federal court oversight. City Hall staffers even coined a new word to describe her leadership: Quan-fusion.

Among Quan's 17 challengers is Oakland City Councilwoman Rebecca Kaplan, who decided to join the race last week.

The collision comes a week after KRON TV's Stanley Roberts, host of the popular "People Behaving Badly" segments, broadcast two reader-submitted pictures showing Quan using her cell phone without a hands-free device while driving.

In a subsequent interview with Roberts, Quan acknowledged that she had been using her cell phone despite hands-free features in her cars.

"I work like 24/7. I go to a lot of meetings and go to a lot of different events," Quan told the station. "My staff and I are thinking about maybe I really need a driver because I'm working so long. It's very easy, unconsciously, to do things like that."

She continued, "You forget that I have paparazzi everywhere. In this case, I'll say thank you to them. People take pictures of me all the time, and so it was a good reminder that we all need to be safe."

She said she was "chastened and apologetic." Asked if she would use her phone again while driving, the mayor said, "I'm going to try not to."

Chronicle staff writers Chip Johnson and Will Kane contributed to this report.