Two U.S. senators on the Committee on Commerce, Science and Transportation sent a letter Thursday to the CEO of embattled Japanese parts supplier Takata Corp. demanding documents linked to its faulty air bags that they had requested by mid-December.

In the letter to Takata CEO Shigehisa Takata, committee Chairman John Thune and ranking member Bill Nelson said the Japanese company had not "fully addressed" a previous request by the committee in November for the documents.

The senators said that although Takata met with committee members on March 4, the company had still not delivered some of the documents related to the air bags that can improperly inflate and hurl metal fragments.

In addition to information on a safety inspection of a Mexican factory, corporate organizational charts and the company's document retention policy, the senators said they are still waiting for a Takata plant supervisor's email from March 2011 possibly warning about the faulty air bags.

Thune and Nelson asked Takata to deliver the remaining documents it has requested by Friday about the defect linked to six deaths and multiple injuries in the United States.