Federal regulators have issued warnings to Plains All American Pipeline Co. for “probable violations” related to the rupture in May of an oil pipeline on the Santa Barbara coast that spilled up to 3,400 barrels of crude.

Officials with the federal Pipeline and Hazardous Materials Safety Administration said the company was unable to provide records of its internal safety evaluation of the pipeline that failed or that documented steps to ensure supervisors were familiar with safety procedures, and had not maintained adequate records of pressure-testing of tanks designed to handle surges.

Plains also was not able to provide information satisfactory to the inspectors about how procedures its employees were supposed to follow when inspection devices detected evidence of wear or corrosion in the pipeline. The pipeline runs from the coastal community of Sisquoc, near Santa Barbara, to San Emidio, in Kern County.

Regulators also expressed concern that the company’s employees did not appear to be familiar with the “one-call” system in California designed for reporting digging operations to the state.

A spokesperson for the Texas-based company said it is working to address the issues raised by the regulators.