CIUDAD JUAREZ, Mexico  —  Mexican soldiers arrested nine police officers who were allegedly carrying drugs in their patrol cars in the violence-plagued city of Ciudad Juarez, just south of El Paso, Texas.

The officers were detained over the weekend while carrying marijuana and radios with non-police frequencies, Mayor Jose Reyes and municipal Public Safety Department spokesman Jaime Torres said Monday.

"We know there are officers who aren't upright and are breaking the law," Reyes said. "Our job is to identify them and fire them, and to support the federal authorities in their efforts."

Last week, the government sent more than 2,500 soldiers and federal police to crack down on soaring violence in the border state of Chihuahua, where Ciudad Juarez is located.

About 200 people have been killed in the city of 1.3 million so far this year, and 47 policemen have resigned or requested retirement in the last month.

Chihuahua is also home to the town of Palomas, across from Columbus, New Mexico, where at least 40 people have been killed since Jan. 1. Palomas' police chief recently sought asylum in the U.S. after his deputies abandoned him and he received death threats.