The U.S. National Highway Traffic Safety Administration on Wednesday ordered air bag supplier Takata Corp to expand its regional recall of driver-side air bags to cover the entire United States.

Such a nationwide recall would affect vehicles made by five automakers: Ford Motor Co; Honda Motor Co; Chrysler Group LLC, a unit of Fiat Chrysler Automobiles; Mazda Motor Corp and BMW AG.

NHTSA gave Takata until Tuesday to issue a recall. If the company does not, NHTSA "may begin proceedings" leading to fines for the Japanese air bag supplier of up to $7,000 per vehicle that the U.S. road safety regulator says should have been recalled.

But NHTSA is limited and cannot fine a company more than $35 million. The U.S. Department of Transportation which includes NHTSA, has asked Congress to raise that limit to $300 million.

The letter follows a Nov. 18 press conference in which NHTSA Deputy Administrator David Friedman said the regulator would tell Takata to issue a nationwide recall for driver-side air bags made by the five automakers.

NHTSA has made no estimate of the number of vehicles that would be included in such an expanded recall. The regional recalls have involved about 4.1 million vehicles.

A letter from NHTSA to Takata Senior Vice President Kazuo Higuchi obtained by Reuters said Takata's previous recall limited to areas of high humidity should be expanded because of incidents reported in California and North Carolina that are outside of the initial regional recall area.

Takata has resisted expanding the recall for driver-side air bags beyond the initial regional "high humidity" area.

Takata's U.S. spokesman said on Wednesday that the company had no immediate comment to the NHTSA letter.