(Bloomberg) -- BP Plc asked US energy regulators to intervene in its dispute with Venture Global LNG Inc. over liquefied natural gas cargoes, escalating a feud that’s roiled the market for the super-chilled fuel.

The London-based supermajor accused Venture Global of violating its contract by selling cargoes from its plant at Calcasieu Pass in Louisiana through one-off deals rather than supplying customers signed up for long-term deals, according to a letter BP sent to the Federal Energy Regulatory Commission on Monday.

Venture Global began operations at the plant in March 2022 but hasn’t been shipping gas to BP and other energy giants that agreed to deals of 10 years or more, saying the contracts aren’t in effect yet because the facility remains in startup, or commissioning, phase. Instead, the company has sold cargoes into the spot market, where prices are significantly higher.

Read More: Shell, BP Call On US-EU Task Force to Intervene in LNG Dispute

Venture Global “has consistently thrown a veil of secrecy around its operations by refusing to follow the FERC’s regulations,” BP’s wrote in its letter.

Venture Global vowed to file a formal response “in due course,” according to spokesperson Shaylyn Hynes.

“The complaint that BP filed with FERC has no merit and is another attempt — after Repsol tried and failed — to use a federal energy regulator to advance its own interests in a commercial dispute,” Hynes wrote in an email. “BP’s repeated efforts to publicize that dispute show the weakness of its contractual position.”

The delayed shipments have emerged as a mounting point of contention between Venture Global, the developer of key US LNG export terminals, and some of the world’s largest energy companies. It comes as Europe is eager for more fuel heading into winter and as the US is poised to become the biggest global exporter of LNG. Customers including BP, Shell Plc and Repsol SA have initiated arbitration proceedings over the delayed contract start.

(Adds Venture Global’s response starting in fifth pargraph.)

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