A federal agency is issuing regulations aimed at making it easier for the government to shut down bus and truck companies with a pattern of safety problems.

The Federal Motor Carrier Administration said Friday the regulations give the agency authority to put out of business operators who have a history of problems, even if their most recent inspection alone doesn't quite meet the threshold for closure.

Congress told the agency to issue the new regulations in a transportation bill passed in 2012. Safety advocates have long criticized the agency for not being aggressive enough in closing unsafe truck and intercity and tour bus companies.

The National Transportation Safety Board has called for an investigation of the agency, pointing to fatal bus and truck accidents that occurred after agency inspections.