MEXICO CITY – Mexico’s most powerful drug cartel appears to be expanding methamphetamine production on a massive scale, filling a gap left by the breakdown of a rival gang that was once the top trafficker of the synthetic drug.

The globe-spanning Sinaloa cartel is suspected of dealing record tons of drugs as well as the chemicals that are used to make meth, known as precursor chemicals, which are processed in industrial-sized operations.

The apparent increase in the Sinaloa group’s involvement comes as the Mexican government says it has dismantled the La Familia gang with key arrests and killings of its leadership. It also coincides with U.S. drug intelligence reports showing that Mexico is once again the primary source of meth to the United States.

Methamphetamine production, gauged by seizures of labs and drugs in Mexico, has increased dramatically since 2008.

Mexican authorities have made two major busts in as many months in the quiet central state of Queretaro. In one case, they seized nearly 500 tons of precursor chemicals. Another netted 3.4 tons of pure meth, which at $15,000 a pound would have a street value of more than $100 million.

Authorities said they couldn’t put a value on the precursors, which were likely headed for an industrial processing lab found 12 feet underground in a farm field in the cartel’s home, the northwestern state of Sinaloa.

Steve Preisler, an industrial chemist who wrote the book “Secrets of Methamphetamine Manufacture” and is sometimes called the father of modern meth-making, said “the quantity is just amazing.”

“It is a huge amount of starting material which would allow them to dominate the world market,” said Preisler, who served 3½ years in prison more than 20 years ago, in an email to the Associated Press.

He added that the most efficient production methods would yield about half the weight of the precursors in uncut meth, or 200 to 250 tons, which could be worth billions of dollars.

Officials of Mexico’s federal police, army and Attorney General’s Office refused to comment on who owned the meth lab or precursor warehouses.

Meth availability in the U.S. has rebounded since a drop in 2007 and is directly related to production in Mexico, according to the U.S. Justice Department.

Meth seizures remained roughly level in the U.S. at 8.16 tons in 2008 and 8.27 tons in 2009. But Mexico went from seizing 0.37 tons in 2008 to 6.72 tons in 2009, the U.N report said.

Authorities seized 200 tons of precursor chemicals in the Pacific seaport of Manzanillo last year, a raid that the Attorney General’s Office described at the time as the largest in Mexican history. The Queretaro seizure last month was double that.

The volume “suggests that it is not solely for U.S. and domestic consumption,” the report said.

The Mexican government says its offensive against La Familia, a pseudo-religious gang based in the western state of Michoacan that was once the country’s main meth producer, is one of the key successes in its crackdown on organized crime and drug trafficking.

Founder Nazario Moreno Gonzalez was killed in a two-day shootout with federal police in December. His right-hand man, Jose de Jesus Mendez Vargas, who allegedly ran the meth operations, was arrested in June.

But other gangs may now be trying to fill the void.

The Sinaloa cartel, headed by fugitive drug lord Joaquin “El Chapo” Guzman, tends to think big: In mid-July, Mexican soldiers found a 300-acre marijuana field in the western state of Baja California, the biggest such plantation in the country’s history.

But nobody was prepared for the size of the meth network officials found in industry-heavy Queretaro, one of Mexico’s safest states in terms of drug violence. The two seizures were related, the U.S. official said, and came out of the arrest of a local meth distributor months ago.

When soldiers raided three connected warehouses June 15, they thought they had found 1,462 50-gallon drums filled with precursors. But when experts examined the stash, they found 3.4 tons of pure meth.

Some speculate that the Sinaloa cartel is trying to reach even beyond the United States. Police in Malaysia arrested three Mexican brothers in March 2008 at a secluded meth factory along with a Singaporean and a Malaysian, and seized more than 60 pounds of methamphetamine.

Such an Asian connection would be a natural link for the cartel, since most of Mexico’s precursor chemicals come from the region.