SAN DIEGO — Two drug-smuggling tunnels with rail systems stretching hundreds of yards across the U.S.-Mexico border were discovered this week by law enforcement officials, federal authorities said Friday.

No contraband was found in connection with the tunnels, which linked warehouses in Tijuana, Mexico, and the Otay Mesa area of San Diego, according to a statement from U.S. Immigration and Customs Enforcement’s Homeland Security Investigations.

The first tunnel, stretching about 600 yards, was discovered Tuesday. The other tunnel, located Thursday, stretches more than 700 yards.