HOUSTON, Feb 21 (Reuters) - Three of Venture Global LNG's major customers have asked U.S. energy regulators to address the LNG developer's request for an one-year permit extension to complete a Louisiana export facility, signaling their intention to voice concerns.

The LNG developer last week asked for a one-year extension to complete its Calcasieu Pass gas-export plant, or to receive assurances it did not need an extension.

BP PLC, Shell PLC and Repsol SA are requesting to weigh in on the request, according to documents filed on Wednesday with the Federal Energy Regulatory Commission (FERC). All three have filed contract arbitration claims against Venture Global over a lack of contracted cargoes.

Shell said it has deep concerns about Venture Global's conduct and "intends to file comments or a protest in response."

The existing FERC authorization expires on Feb. 21, but the Arlington, Virginia-based company has said the plant's commissioning phase will not be concluded until late this year.

A Venture Global LNG spokesperson called the requests "unnecessary and premature," adding: "We thank our stakeholders - including BP - for their continued interest.”

The company's Calcasieu Pass export facility has been processing gas for export since March 2022. But it considers the facility not fully operational and is allowed under its contracts to sell pre-commission cargoes. (Reporting by Curtis Williams in Houston; Editing by Josie Kao)