SAN FRANCISCO (Reuters) - The U.S. retail industry's main lobby group voiced its strong opposition to employer mandated health care coverage on Thursday 9 July, pitting itself against Wal-Mart Stores Inc, the world's largest retailer, which has said it would support such a measure.

The National Retail Federation "cannot support an employer mandate of any type," said NRF Senior Vice President for Government Relations Steve Pfister in a statement.

He said the retail industry is a labor-heavy one that operates on a thin profit margin.

"Employer mandates of any kind amount to a tax on jobs," Pfister said. "We cannot afford to have new and existing jobs priced out of our collective reach because of mandated health coverage."

President Barack Obama is pushing for an overhaul of the $2.5 trillion U.S. healthcare system. He has made a healthcare plan that would rein in costs and cover most of the roughly 46 million uninsured Americans one of his top priorities.

While the president has left many of the details of health reform to Congress, he has told U.S. lawmakers he is open to requiring larger companies to provide coverage for employees but exempting smaller businesses.

Last week, Wal-Mart, which is not a member of the NRF, said it supports the push to require large employers to offer health insurance to workers.

"We are for an employer mandate which is fair and broad in its coverage," it stated in a letter signed by Mike Duke, its chief executive officer.

Wal-Mart said it supports an employer mandate that covers as many businesses as possible, as well as part-time and full-time employees. The requirement would ultimately save companies money, it said.

(Reporting by Nicole Maestri, editing by Gerald E. McCormick)