Pemex and the government of President Andres Manuel Lopez Obrador said earlier this year that the Dos Bocas refinery built in Tabasco state would start producing gasoline and diesel in the first quarter.
The refinery, which has been running behind schedule and over budget, is part of Lopez Obrador's strategy to wean the country off expensive gasoline and diesel imports.
Last month, Pemex numbers showed that its crude oil production in February had fallen to its lowest level in 45 years, curtailing available supplies for the nation's six local refineries already operating.
"They either refine it or export it. There is not enough crude for both," a person familiar with the matter told Reuters.
The cancellations will reduce exports of Mexico's flagship Maya crude by 122,000 bpd, Isthmus by 247,000 bpd and Olmeca by 67,000 bpd, the document showed.
It was not immediately clear if more cargo cancellations would occur after April, but one of the sources said the availability of Maya had been dwindling for some time and was unlikely to be resolved soon.
The cancellations will affect term contract customers in Europe, the United States and Asia, the source said. A second source confirmed this.
Pemex did not immediately respond to a request for comment.
Mexico's energy ministry expects the Dos Bocas refinery to process an average of 178,600 bpd of crude oil this year. While the refinery is operational, it does not yet produce finished fuels.
In total, the energy ministry numbers show domestic crude oil processing is expected to increase from 713,300 bpd in 2023 to an average of 1.04 million bpd this year.
At the end of the year, Pemex CEO Octavio Romero has said local refineries - including the Dos Bocas refinery - would process 1.7 million bpd.
