Mazda and Ford operate the AutoAlliance International plant in Michigan as a 50-50 partnership. Citing unnamed company sources, the Nikkei said Mazda is considering selling its stake to Ford as the Japanese automaker tries to restructure its global production.
Mazda cars sold in the U.S. will be shipped from Japan and Mexico starting around 2013, according to the Nikkei.
In response, Mazda issued a short statement saying the report was not based on information it had released.
"Mazda and Ford are jointly studying various possibilities for AAI, and we have nothing to announce at this time," Mazda said. "We do not comment on speculation."
The plant in Flat Rock, Michigan manufactures the Mazda6 midsize sedan and the Ford Mustang. It employs about 1,700 workers, according to Ford.
The U.S. automaker has essentially agreed to maintain current worker levels by expanding the models it builds at the facility, Nikkei said.
The two companies loosened their longtime auto alliance last year when Ford cuts its stake in Mazda from 11 percent to 3.5 percent. At the time, Mazda President Takashi Yamanouchi insisted that the two companies would continue to cooperate through joint ventures and technology exchanges.
Mazda's latest financial results revealed tough times for the Hiroshima-based company.
Its net losses swelled to 60 billion yen ($742 million) in the fiscal year ended March 31, from 6.5 billion yen the previous year. The company blamed a persistently strong yen and lackluster sales in Japan, as well as the March 11 earthquake and tsunami that disrupted auto production.