Auturo Sarukhan, the Mexican ambassador to the United States, repeated and defended his claim that 90 percent of the weapons intercepted in Mexico come from the U.S.

During an appearance on CBS' "Face the Nation" Sunday, Sarukhan said on the Arizona and Texas borders with Mexico alone, roughly 7,000 licenses for federal firearms had been granted.

"And a lot of the weapons that are being bought by the drug syndicates, either directly or through proxy purchases, are coming from those gun shops," he said.

Sarukhan isn't the only one to cite this myth. Secretary of State Hillary Clinton, California Sen. Diane Feinstein and Willliam Hoover, assistant director for field operations at the Bureau of Alcohol, Tobacco, Firearms and Explosives have all said that 90 percent of weapons used to commit crimes in Mexico come from the U.S.

But in fact, only 17 percent of guns found at Mexican crime scenes have been traced to the U.S.

An ATF spokeswoman told FOXNews.com earlier this month in a clarification of the statistic used by her own agency's assistant director "that over 90 percent of the traced firearms originate from the U.S."

But a large percentage of the guns recovered in Mexico do not get sent back to the U.S. for tracing because it is obvious from their markings that they do not come from the U.S.

"Not every weapon seized in Mexico has a serial number on it that would make it traceable, and the U.S. effort to trace weapons really only extends to weapons that have been in the U.S. market," Matt Allen, special agent of the U.S. Immigration and Customs Enforcement (ICE), told FOX News earlier this month.

Sarukhan has claimed that Mexico seizes 2,000 guns a day from the United States, or 730,000 a year. But the official statistic from the Mexico attorney general's office says Mexico seized 29,000 weapons in all of 2007 and 2008.

On "Face the Nation," host Bob Schieffer asked Sarukhan for evidence to support his claim that most of the weapons seized are coming from the United States.

"The data we have is the one that we've been sharing with our counterparts in the U.S. government, ATF and the Justice Department, and other agencies that have been working with us to determine where those guns are coming from," Sarukhan replied.

For example, Sarukhan cited the Mexican border town of Reynosa where he said more than 250 assault weapons and half a million rounds of ammo were seized in November.

"These had just crossed over the border from the United States in Mexico," he said. "By tracing these weapons, by looking at the types of weapons, we're determining that most of these weapons are coming from the United States."