WASHINGTON — Spurred by a series of fiery train crashes, a push by government and industry to make safer tank cars used for shipping crude oil and ethanol has bogged down in squabbling and finger-pointing over whether they’re needed and if so, who should pay.

The Transportation Department, worried about the potential for catastrophic accidents involving oil and ethanol trains that are sometimes as many as 100 cars long, is drafting new tank-car regulations aimed at making the cars less likely to spill their contents in the event of a crash. But final rules aren’t expected until late this year at the earliest, and it is common for such government rulemaking to drag on for years.

But one safety official said urgent action is needed.

The Obama administration needs to take steps immediately to protect the public from potentially catastrophic oil train accidents even if it means using emergency authority, Deborah Hersman, chairwoman of the National Transportation Safety Board, said Wednesday.

“We are very clear that this issue needs to be acted on very quickly,” she told reporters at the conclusion of a two-day forum the board held on the rail transport of oil and ethanol. “There is a very high risk here that hasn’t been addressed.”

The Transportation Department said in a statement in response to Hersman that “safety is our top priority, which is why we’re putting every option on the table when it comes to improving the safe transport of crude oil by rail.”

The freight railroad industry proposed tougher tank-car standards last fall, and recently upped its proposal another notch. The government and the Association of American Railroads say oil being shipped from the booming Bakken region of North Dakota and Montana may be more volatile than previously thought.

But oil companies – which own or lease the tank cars, and would have to bear much of the cost of tougher standards – want to stick to voluntary standards agreed to by both industries three years ago unless it can be shown that new standards are needed, American Petroleum Institute officials said. The railroads, they say, are refusing to share the “scientific basis” for their proposal.

The petroleum institute wants “a comprehensive examination” of changes proposed by the rail industry, including whatever computer-modeling was used to support tougher standards so that it can be peer-reviewed, said Brian Straessle, a spokesman for the institute. “So far, no data has been provided.”