The plantation is four times larger than the previous record discovery by authorities at a ranch in northern Chihuahua state in 1984.

The pot plants sheltered under black screen-cloth in a huge square on the floor of the Baja California desert, more than 250 kilometers south of Tijuana, across the border from San Diego.

Army Gen. Alfonso Duarte said the screening, which is often used by regular farmers to protect crops from too much sun or heat, made it difficult to detect from the air what was growing underneath.

It was only when soldiers on the ground reached the isolated area Tuesday that they found thousands of pot plants as high as 2.5 yards (meters) tall. The average height of the plants was about 1.5 yards (meters). Duarte said they were not yet ready for harvest.

AP