DETROIT (Reuters) - Honda Motor Co (>> Honda Motor Co Ltd) is in talks with two air bag suppliers to help it stock replacement parts for defective Takata Corp (>> Takata Corporation) air bags, the Wall Street Journal reported on Friday, citing people aware of the planning.

On Thursday, Takata's senior vice president for global quality assurance, Hiroshi Shimizu, told a U.S. Senate panel the company may not be able to keep up with demand for replacement parts.

About 16 million cars with Takata air bags have been recalled worldwide, with more than 10 million of those in the United States.

Shimizu said that even if the company ramps up production of replacement kits beyond the current pace of 300,000 a month, it may still not have enough parts. "Even if we increase to 450,000, maybe still that's not speedy enough," he said.

David Friedman, deputy administrator of the U.S. National Highway Traffic Safety Administration (NHTSA), told the Senate committee his agency is in touch with two other suppliers to determine whether they are able to make replacement parts.

Friedman agreed with comments made by a senator on the panel that at a rate of 450,000 replacement parts per month, it would take two years to fix all of the possibly defective air bags in U.S. cars that have been recalled.

Friedman told senators that it is not easy for a supplier other than Takata to make air bags that would fit into recalled cars and ensure they are safe.

"We are in contact with two different air bag suppliers," Friedman said on Thursday. "We are asking them what their capacity is, what their compatibility is. There may need to be tests involved to ensure, because each air bag is tuned for each car, that they will be safe."

If the Takata recalls are expanded, as some senators said they want, even more help from outside Takata would be needed, said Scott Upham, analyst at Valient Automotive Market Research.

"A nationwide recall of both Takata driver and passenger inflators would affect over 18 million vehicles globally and require over 36 million inflator replacement kits," Upham said on Thursday.

He added Takata competitors TRW Automotive (>> TRW Automotive Holdings Corp.), Autoliv Inc (>> Autoliv Inc.) and Daicel Corp (>> Daicel Corp) would be required to help make all those kits by the end of 2015.

(Reporting by Bernie Woodall; Editing by Peter Galloway)