Federal agents found a tunnel running under the U.S.-Mexico border in Nogales, the second discovered in a week, and seized more than 181 kilos (400 pounds) of marijuana, the Border Patrol said.

The tunnel was discovered Monday at an apartment building near the border, the Border Patrol's spokeswoman in the Tucson sector, Crystal Amarillas, told Efe.

The 97-meter (319-foot) tunnel ran 67 meters (219 feet) into the United States and 31 meters (about 100 feet) into Mexican territory.

This tunnel, which had electricity, a ventilation system, reinforced walls and a hydraulic system, was more sophisticated than the one found last week in the same area, Amarillas said.

Agents found 26 bales of marijuana worth $215,000 inside the tunnel.

Mexican security forces seized 45 kilos (about 100 pounds) of marijuana on their side of the border and arrested a suspect, Amarillas said.

Criminal organizations have been forced to resort to tunnels because of the high likelihood of being detected by the Border Patrol and the severe penalties traffickers face if caught and convicted, Amarillas said.

Since the mid-1990s, authorities have discovered many clandestine tunnels along the border, with more than 70 drug tunnels being found in the past four years.

People traffickers and drug cartels often use clandestine tunnels to cross the vast U.S.-Mexican border, which runs 3,200 kilometers (1,988 miles).

Arizona is one of the main crossing points for illegal drugs and migrants along the U.S.-Mexico border.

A total of 12 tunnels were found on the border between Arizona and Mexico in fiscal year 2011, which ended on Sept. 30.

This is the second tunnel found in the area in the current fiscal year.

In May, Mexican army troops found a tunnel in San Luis Rio Colorado, a city in Sonora state, that was being constructed to smuggle drugs and people into the United States, but no arrests were made.

The tunnel was designed "to move people and drugs toward the United States of America, as well as (to smuggle) arms and American money into national territory," the Defense Secretariat said.

A sophisticated "narcotunnel" equipped with lighting and ventilation systems was found on May 5 running under the border between Arizona and Mexico by agents from the U.S. Border Patrol's Tucson sector.

The tunnel, which was found with the assistance of Mexican authorities, started inside an abandoned building in Nogales, a border city in Mexico's Sonora state.

Last week, U.S. authorities announced the discovery of a drug tunnel linking San Diego, California, and neighboring Tijuana, Mexico, and the seizure of nearly 18 tons of marijuana.

The tunnel linked an unfinished building near Tijuana's international airport and a warehouse in the Otay Mesa area of San Diego.

Mexican army troops found a tunnel in March in Mexicali, the capital of Baja California state, that was used to move drugs and illegal immigrants under the U.S.-Mexican border.

The tunnel was built about three kilometers (1.8 miles) from a U.S. immigration control post.

In December 2008, a woman was rescued by U.S. Border Patrol agents from a clandestine tunnel that collapsed as she tried to cross from Tijuana, a border city in Baja California, into the United States illegally.

In March 2007, Mexican police found a clandestine tunnel crossing under the border between Tijuana and Otay, California.

The tunnel was under construction from the Tijuana side of the border and had penetrated three meters (about 10 feet) into U.S. territory.

Seven people were rescued from a tunnel beneath the U.S.-Mexican border after being trapped for several hours in October 2006.

All seven were trapped in the tunnel connected to the sewerage network when it collapsed near the border crossing into San Ysidro, California, across the border from Tijuana.

In 2005, Mexican police discovered a tunnel, apparently used by people traffickers, linking Mexico and the United States beneath the heavily patrolled and partially walled-off border.

The tunnel, which was located near the wall that separates Mexico and the United States, in an area of Tijuana known as Ciudad Industrial, was sealed off on both sides of the border.