* Mazda expects U.S. to tighten emissions, fuel-economy testing
* Tougher U.S. tests to cause delays for diesel plans -Mazda exec
* Mazda remains committed to U.S. diesel rollout -executive
By Norihiko Shirouzu and Maki Shiraki
TOKYO Oct 29 (Reuters) - Mazda Motor Corp expects delays to the launch of diesel-powered cars in the United States in the wake of the Volkswagen AG emissions test-rigging scandal, but it remains committed to a rollout, a senior executive said.
Kiyoshi Fujiwara, a Mazda managing executive officer in charge of research and development and cost innovation, said media reports that Mazda had given up on diesel's potential use in the U.S. market were untrue.
The U.S. launch of Mazda diesel cars, originally planned for 2016, will nevertheless likely be delayed because regulators there are expected to add extra steps to emissions and fuel-economy testing processes, he said.
"We're committed to launching diesel-fuelled cars in the United States," Fujiwara told Reuters in an interview on the sidelines of the Tokyo Motor Show. "There is no doubt about that."
But the tougher testing, he said, "will cause a delay in plans for everybody looking to sell diesel cars in the U.S. market. That's why we cannot say when we are going to be able to launch our diesel cars in the U.S. market at this point."
The expected delay reflects an increasingly complicated regulatory environment for diesel technology in the wake of the Volkswagen scandal.
Diesel had been seen, especially among European carmakers, as a mainstream technology to help meet tougher fuel economy and emissions regulations. But now it looks vulnerable.
"Anybody can, with certainty, guess what's going to happen," Nissan Motor Co CEO Carlos Ghosn told reporters on Wednesday.
"This scandal is not going to make diesel more popular in the United States. This scandal is not going to make diesel more popular in Japan."
Many auto executives and engineers, however, said diesel was far from finished.
"Diesel has its merits," Toyota Motor Corp President Akio Toyoda told reporters on the sidelines of the auto show on Wednesday. "It would be wrong if the ongoing scandal led to the end of diesel use."
Mazda's Fujiwara said U.S. regulators had not notified Mazda of any changes to their testing processes, but the company believes that they have already been toughened and that a delay to its diesel launch plans is unavoidable.
"Tests are going to be tougher," he said. "Regulators are not telling us or anybody what additional testing steps they have added to the processes."
"They no longer trust companies and are not telling us anything. Most likely there is a delay. We just don't know how big a delay it is going to be." (Reporting By Norihiko Shirouzu and Maki Shiraki in Tokyo; Editing by Edmund Klamann)