Canadian Pacific railroad wants the Justice Department to investigate whether other major freight railroads are improperly coordinating opposition to its proposed acquisition of rival Norfolk Southern.

Canadian Pacific said Tuesday that it sent a letter to regulators asking them to investigate after executives from other major railroads said they had discussed the proposed deal.

Canadian Pacific says it believes that conversations between executives from Union Pacific, BNSF and CSX railroads may have violated antitrust rules, especially since Norfolk Southern has rejected all of its offers to date.

Union Pacific spokesman Aaron Hunt says executives talked with other railroads to prepare to petition the government in opposition of any deal.

CSX officials declined to comment, and a BNSF spokesman didn’t immediately respond to a question about Canadian Pacific’s request.