U.S. natural gas pipeline exports to Mexico fell to their lowest level since June 2015 due to maintenance on the NET Mexico pipe in Texas, while the first tankers from the United States started delivering LNG to Mexico's Gulf Coast.

A unit of Mexico's state-owned petroleum company, Petroleos Mexicanos (Pemex), started importing LNG from Cheniere Energy Inc.'s (NYSE MKT: LNG) Sabine Pass export terminal in Louisiana to Mexico's Altamira import terminal on the Gulf of Mexico earlier this month.

"Pemex started importing gas through Altamira due to maintenance on NET Mexico," Pemex spokeswoman Erika Contreras Licea told Reuters, noting the company scheduled the work to start during Holy Week (April 9-15) when demand is lower. She said the work was expected to last about a week or so.

Exports fell to around 2.4 billion cubic feet per day (Bcf/d) over the past three days, the lowest level since June 2015. That compares with an average of 3.8 Bcf/d during the 30 days prior to the reductions, according to Reuters data.

"Deliveries from Tennessee and NGPL into NET Mexico fell to zero over the back half of the weekend," said Luke Larsen, vice president for markets at energy data provider PointLogic Energy, noting that the flows started to decline after April 9.

Tennessee and Natural Gas Pipeline Co. of America (NGPL) are both owned by Houston-based energy company Kinder Morgan Inc. (NYSE: KMI).

So far, the Creole Spirit LNG tanker, with a capacity to hold about 3.6 Bcf of gas, and the Magellan Spirit, with a capacity of around 3.3 Bcf, delivered cargoes from Sabine to Altamira on April 4 and April 14, respectively.

The Methane Nile Eagle, meanwhile, is sitting off the coast of Altamira with about 2.9 Bcf of gas from Sabine.

Both the Creole Spirit and Magellan Spirit were heading for the Panama Canal before turning north toward Altamira.

The LNG sellers would likely be the companies that chartered the ships, including units of Cheniere (Creole Spirit) and Royal Dutch Shell Plc (Methane Nile Eagle), according to Ted Michael, LNG analyst at Genscape Inc.

The 2.1-Bcf/d NET Mexico pipeline from Texas to Mexico is owned by NET Midstream, a unit of NextEra Energy Partners LP (NYSE: NEP). NEP is part of NextEra Energy Inc. (NYSE: NEE).

The pipeline is anchored by a long-term agreement with a unit of Pemex Gas y Petroquimica Basica, Mexico's state gas company, which is a unit of Pemex.