U.S. Customs and Border Protection is looking into concerns by New Mexico's top land manager about whether federal agents can access a milelong stretch of state land along the U.S.-Mexico border.

Federal officials sent New Mexico Land Commissioner Aubrey Dunn a letter this month about his concerns over the installation of a border wall, infrastructure and roads on state trust land years ago. The letter released Thursday says the agency is gathering records and plans to meet with Dunn in early April.

Karl Calvo, an assistant commissioner that oversees Customs and Border Protection's facilities and assets, said in the letter that the agency values its relationship with the State Land Office.

"An important part of CBP's strategy to successfully secure the nation's borders includes developing and leveraging partnerships and dialogue with state and local stakeholders to ensure that the unique operational needs of each region are effectively met," Calvo wrote.

The letter was sent to Dunn, who is running for U.S. Senate, after he posted signs and cordoned off the land along the border. Dunn said his office was forced to take action in early March after the U.S. government failed to respond to his previous correspondence.

Dunn contends the federal government never got the needed authorization to access the state land and has not compensated New Mexico for using the property. He has called it a state sovereignty issue and said revenue earned from development or use of state trust land helps fund public education.

"I am confident we can agree upon terms that will enable us to collect revenue for New Mexico schoolchildren and them to manage their national security operations," Dunn said in a statement Thursday.

The debate about installing more fencing along the border heated up recently when a federal judge sided with the Trump administration over a challenge to building barriers in parts of California and New Mexico. There's no timeline for when work might begin to replace fences along a 20-mile (32-kilometer) stretch near Santa Teresa, New Mexico.

The State Land Office began researching the effects that construction could have after some Democratic lawmakers proposed legislation aimed at blocking construction on New Mexico trust land. The land office oversees millions of acres, including a patchwork along the state's border with Mexico.

Dunn's staff determined that a parcel between the Santa Teresa port of entry and El Paso, Texas, was initially given to what was then the territory of New Mexico under the 1898 Ferguson Act.

New Mexico officials contend the parcel was never part of the buffer zone established by a 1907 presidential proclamation to ensure federal authorities could patrol along the southern border.