The U.S. ambassador to Mexico is warning U.S. citizens traveling in Mexico to use caution because of increasing violence and criminal activity, especially along the 3000-kilometer border.  The warning comes at a time when people in one border town are observing an especially painful anniversary related to cross-border crime.

In a statement, Ambassador Tony Garza says violence in the border region threatens both Mexicans and Americans and their way of life. He says violence related to narcotics smuggling has claimed 1,500 Mexican lives this year.

He says that, just last week, six young men, one of them a U.S. citizen, died in a gang-related shootout.

He also cites the numerous kidnappings of U.S. citizens that have taken place in the Mexican city of Nuevo Laredo, which is just across the border from Laredo, Texas. He says more than 20 of the cases remain unresolved.

The ambassador's letter comes at an especially difficult time for one family in Laredo.  Two years ago, Saturday, Brenda Cisneros and her friend, Yvette Martinez, crossed the border to celebrate her birthday at a Nuevo Laredo club. Neither of the young women has been seen since. 

Saturday is Brenda's 24th birthday, and the second anniversary of her disappearance. Speaking to VOA by telephone, her father, Pablo Cisneros says his family faces a difficult day.

He says, this will be a very painful day for them all.  He says he believes his daughter was kidnapped by corrupt policemen in Nuevo Laredo, and then turned over to drug-smugglers. He said her ability to speak both English and Spanish may have made her useful to the drug-traffickers.  Law enforcement officials, however, believe it is also possible the women were kidnapped and forced into prostitution.

Pablo Cisneros heads an organization in Laredo called Laredo's Missing, through which families of some 40 U.S. citizens who disappeared in Mexico are seeking help in finding their loved ones.  He says there are more than 400 Mexican citizens in the Nuevo Laredo area, who are missing, and that Mexican authorities have provided little help.

He adds that his group has gotten no answers from Mexican authorities, and its members hope the U.S. government can exert some pressure on Mexico to resolve the cases.  Earlier this year, Mexican President Vicente Fox sent soldiers to Nuevo Laredo to quell violence there, but Pablo Cisneros says the violence has not abated.

He says the military operation is now over, and the criminals are still there, operating, he says, with the help of corrupt police officers.

Both Mexican and U.S. business leaders and local officials in the border area lament the violence.  They say it has not disrupted commerce there. Laredo continues to be the most active land-based port of entry for the United States, with millions of dollars in goods passing back and forth over the border every day.  Citizens from both countries also continue to pass back and forth between Laredo and Nuevo Laredo to do business, or visit friends and relatives.

But Ambassador Garza warns that the pace of normal cross-border life could be disrupted, if Mexican authorities fail to bring the situation under control. He says, "the crimes put a strain on travel and tourism, on the business and investment climate, and on the bilateral relationship we share."

There has been no reaction from the Mexican government to the ambassador's statement, but, in the past, government spokesmen have noted efforts by the Fox administration to fight drug trafficking, as well as illegal smuggling of guns from the United States to Mexico.