Updated

U.S. authorities on Tuesday reported a spike in seizures of guns and cash along the Mexican border since they began assigning more agents to stem the flow of southbound contraband.

Nearly 600 illegal weapons were seized along the border by U.S. Immigration and Customs Enforcement and U.S. Customs and Border Protection officials from March through September, an increase of more than 50 percent from the same period of 2008.

The agencies seized more than $40 million in cash along the border from mid-March through September, nearly double the amount in the year-ago period.

The seizures represent a tiny fraction of business done by Mexican and Colombian drug lords. According to the U.S. Drug Enforcement Administration, those drug lords generate $18 billion to $39 billion in wholesale drug proceeds in the United States each year. Cash proceeds are smuggled across the border to Mexico.

But U.S. officials said the figures demonstrate that heightened enforcement is paying off.

"The increases in seizures is no coincidence," said John Morton, Homeland Security Department's assistant secretary for ICE. "It's a direct result of increased resources, increased emphasis that we are placing on the southwest border."

Senior officials from immigration, border patrol and the Bureau of Alcohol, Tobacco, Firearms and Explosives are meeting in San Diego through Wednesday to discuss ways to combat the flow of guns and drug proceeds south of the border amid Mexican President Felipe Calderon's nationwide crackdown on drug traffickers.

Mexico asked U.S. authorities to trace 12,073 firearms last year, up from only 2,906 in 2007 and 2,654 in 2006, according to the ATF. Of those successfully traced, the firearms bureau said about 90 percent came from the United States.

Kenneth Melson, acting director of the ATF, said lack of training in Mexico is the main obstacle to increasing weapons traces even more. Weapons tracing involves entering serial numbers and other information into a special computer system.

"I think (Mexico's) intent is to try to give them all to us," Melson said in an interview. "They're just not in a position to be able to do that right now ... It's a huge effort."

A Spanish-language version of eTrace, the Web-based method of submitting tracing information, is expected to be available by the end of this year.