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.

Although Venture Global started up its Calcasieu Pass liquefied natural gas plant in Louisiana almost two years ago, it has yet to send a single cargo under long-term contracts. Instead, the company has been shipping LNG on a spot basis, citing operational issues that have prevented full service. Shell and BP have both said in filings that Venture Global has made more than $18 billion on cargoes that should have been sold to customers under contract. 

BP and Shell’s actions constitute “unseemly behavior” and the regulatory process was not meant to exert commercial pressure on a contractual matter, Venture Global spokeswoman Shaylyn Hynes said Wednesday. Venture Global continues to be transparent and in compliance with contractual and regulatory obligations, Hynes said. 

The company called BP’s claims “baseless and demonstratively false” in a Jan. 2 filing, saying it has kept FERC informed of technical issues and that the plant’s unique design “entails a significantly longer commissioning process” compared with other export terminals.

Shell’s filing also included a comparison of commissioning cargoes shipped from US LNG facilities since 2016, alleging that Venture Global has exported more commissioning cargoes than any other US facility by almost a factor of 10. To date, Calcasieu Pass has exported 239 cargoes, according to shiptracking data compiled by Bloomberg.