July 26 (Reuters) - U.S. railroad Union Pacific ( UNP )

interfered in a federal safety audit after employees were

coached in how to respond, prompting the rail agency to end the

review, the chair of the Senate Commerce Committee said Friday.

Senator Maria Cantwell said she wants answers about Union

Pacific's ( UNP ) actions after the Federal Railroad Administration told

the committee this month it had been was forced to discontinue

its assessment "due to Union Pacific's ( UNP ) actions to undermine the

integrity of the assessment process," Cantwell said.

She asked the company to provide all documentation regarding

the safety culture audit, along with current policies and plans

to improve its safety culture. Union Pacific ( UNP ) did not immediately

respond to a request for comment.