The American Petroleum Institute (API), the U.S. oil and gas industry's main lobby, said it is worried that recent actions by the Mexican government hurt U.S. investors and violate regional free trade agreements.

In a letter to senior U.S. government officials dated June 11, API said U.S. investors have faced difficulties getting permits in Mexico for fuel stations, storage facilities, imported fuel and terminals.

The group urged the officials to push Mexico to honor commitments in the U.S. Mexico Canada Agreement (USMCA), a new trade deal between the three countries that will soon go into effect.

"Recent examples appear to be new regulatory actions that are inconstantly applied or inconsistent with past practice," API said in the letter.

The "actions of discrimination" against API members likely contravene Mexico's commitments to joint investment protection, the group added.

An API spokesman said the lobby remains supportive of the USMCA.

According to Refinitiv Eikon's data, a backlog of tankers waiting to discharge imported fuel in Mexico has eased this month compared with April and May. But there are still some vessels that have been waiting since April to unload, mainly of U.S. LPG, gasoline and jet fuel.

In Mexico's Tuxpan area in the Gulf, where many independent importers own or rent terminals, eight cargoes were waiting to discharge on June 15, compared with 13 vessels two months ago. At neighboring Pajaritos, the main port of entry for imported fuel, 15 loaded tankers were waiting to unload, down from 23 in April, according to the Eikon data.

A shipping source working at an independent terminal in Mexico said Mexican tax authority SAT has been slow to authorize independent fuel imports, saying there are unreported volumes or problems with fuel quality. The SAT did not immediately respond to a request for comment.