Shell Plc is joining rival BP Plc in escalating a feud with Venture Global LNG Inc., asking US energy regulators to intervene in their dispute with the natural gas exporter.

The Federal Energy Regulatory Commission should start a legal proceeding to disclose privileged documents that would reveal more about why Venture Global has delayed full commercial startup of its export plant in Louisiana, Shell said in a filing dated Tuesday. BP lodged a similar complaint with FERC last month. The companies, along with other Venture Global customers, previously filed arbitration cases against the gas supplier in New York and London.