HOUSTON -

A traffic stop Tuesday morning led to the discovery of marijuana and methamphetamine hidden inside a piece of heavy earth moving equipment.

Houston narcotics officers were tipped that the drugs were headed to Houston from the Mexican border on Highway 59 and alerted patrol units to be on the lookout.

A semi-tractor pulling a flatbed trailer carrying an earth excavator was spotted and stopped at 12:45 a.m. on the Southwest Freeway at Beltway 8.

The truck was taken to the police garage behind 61 Reisner Street. Fire fighters used an acetylene torch to cut away the machine's steel skin. Inside they found 600 pounds of marijuana and 13 kilos of methamphetamine.

The truck driver was taken into custody but has not been charged.

Highway59 is a primary smuggling route into the U.S. from Mexico, running from Laredo to Texarkana in northeast Texas.

In May the Fort Bend County Narcotics Task Force recovered 12 pounds of heroin, 24.5 pounds of cocaine, and hundreds of thousands of dollars in cash in four separate incidents on 59.

Three years earlier, Texas Department of Public Safety Troopers seized 22,000 pounds of marijuana valued at more than $9,000,000 after stopping a tanker truck on 59 near El Campo.