Galp Energia logo and stock graph are seen displayed in this illustration taken, May 3, 2022. REUTERS/Dado Ruvic/Illustration/File Photo Acquire Licensing Rights

Portugal oil and gas firm Galp has asked U.S. regulators to allow it to join BP (BP.L) and Shell's (SHEL.L) formal complaints against U.S. liquefied natural gas (LNG) exporter Venture Global LNG, a filing showed on Tuesday.

Shell and BP have asked the Federal Energy Regulatory Commission (FERC) to require Venture Global to disclose plant commissioning data to determine why commercial operation at Venture Global's Calcasieu Pass terminal is stalled.

Galp Trading (GALP.LS), a unit of Galp Energia, said "no other party can adequately represent or protect its interests," in the dispute. It missed a FERC filing deadline and asked to join the two other European firms in petitioning for more details.

Venture Global's Calcasieu Pass export facility has been producing and selling LNG for more than 21 months while telling Galp, Shell, BP and others it cannot provide them with term-contract cargoes while the plant is in commissioning.

The customers have complained that this lack of access has cost them billions of dollars in lost sales.

Galp did not become aware of the FERC proceeding due to what it called administrative oversight, and was unable to file its intervention prior to the Jan. 2, documents show.

Venture Global LNG's contract customers Shell, BP, Edison SpA (EDNn.MI), Polish state energy firm Orlen and Spain's Repsol (REP.MC) have each filed contract arbitration claims against the Herndon, Virginia, exporter.

Venture Global LNG did not immediately respond to a request for comment. It has previously said the letters to FERC by Shell and BP sought to bring a commercial dispute into the political arena.

"This unseemly behavior reflects BP and Shell’s increasing lack of confidence in their contractual positions, and their complete disrespect for the U.S. regulatory process," spokesperson Shaylyn Hynes said at the time.

Venture Global LNG has become a major U.S. exporter of the superchilled gas since it started processing at its Calcasieu Pass, Louisiana, plant early in 2022. It has sold more than 200 cargoes of the gas under its own accounts without supplying BP and other long-term contract customers.