MEXICO CITY — The U.S. State Department said Tuesday it was “concerned about the fair treatment of our companies in Mexico” after Mexican police seized a cargo terminal owned by an Alabama-based company.

Mexico’s seizure of the Caribbean cargo port stretched into its second week Tuesday. Police are holding the port and have apparently used it to unload cargo from a Mexican cement and aggregates company, Cemex.

The Alabama company, Vulcan Materials, said Tuesday that police and prosecutors still had not presented any legal paperwork to justify the seizure.

The State Department said that “cases like these have the potential to impact our ability to achieve our shared vision for improving livelihoods in one of Mexico’s most economically disadvantaged regions. It also impacts Mexico’s efforts to attract future investments.”

The office of President Andrés Manuel López Obrador has not responded to requests to comment on the issue.

The president has been publicly sparring with Vulcan for over a year. He needs the dock to get cement, crushed stone and other materials into the area to finish his pet project, a tourist train known as the Train Maya.

Some of the cement unloaded last week was apparently destined for the Maya Train project, which the president has vowed to open by December despite the fact it is well behind schedule.

Vulcan said police forced their way into the dock at Punta Venado, near Playa del Carmen, last Tuesday.

“It should be clear that the rule of law is no longer assured for foreign companies in Mexico,” the company said in a statement. “This invasion, unsupported by legal warrants, violates Vulcan’s commercial and property rights.”

Vulcan said it had an agreement with Cemex, the Mexican company, to lease it a part of the cargo port, but the agreement expired Dec. 31 and had not been renewed.

Cemex acknowledged the contract had expired, but said it had been trying unsuccessfully to renegotiate it. Cemex said it had three other contracts with Vulcan that were still valid.

Cemex said it filed a criminal complaint against Vulcan and was granted “injunctive relief and a legal warrant to access the property and continue operating” by the state prosecutor’s office.

The wording is odd, since such injunctions are normally issued by Mexico’s federal courts rather than prosecutors, and such disputes are seldom resolved through criminal complaints.

Because there aren’t any local supplies of crushed stone needed to stabilize the Maya Train’s tracks, López Obrador has been forced to import the stone, known as ballast, from Cuba.

Even so, ships carrying the Cuban ballast have to land at the port of Sisal, on the Gulf of Mexico side of the Yucatan peninsula, and be trucked about 180 miles (300 kilometers) to some train construction sites.

The only private freight dock on the Caribbean side that could handle the Cuban shipments — and other shipments of cement and steel — is the one owned by Vulcan. López Obrador has offered to buy the property, but talks have apparently not gone well.

Last May, the Environment Department closed Vulcan’s limestone quarry and forbade the company from exporting stone that has long been used in U.S. and Mexican building projects. The president accused the company of extracting rock and exporting it without proper permits. Vulcan said it has those permits.

López Obrador wants the water-filled quarry to be used as a theme park to rival the nearby XCaret park. He also wants Vulcan to build a cruise ship dock at the freight terminal.

The 950-mile (1,500-kilometer) Maya Train line is meant to run in a rough loop around the Yucatan Peninsula, connecting beach resorts and archaeological sites.

López Obrador touts the train as a way to bring some of Cancun’s tourism income to inland communities that haven’t shared in the wealth. But there are no credible feasibility studies showing tourists will want to use the train.