U.S. officials accused China of being the primary source of synthetic drugs that can easily be obtained through online retailers operating inside the country, including ingredients used by Mexican drug cartels to manufacture methamphetamine, reports The New York Times.

Mexican drug traffickers produce 90 percent of the meth consumed in the United States, according to the Drug Enforcement Agency (DEA), a component of the U.S. Department of Justice.

“Hands down China is No. 1,” an American federal law enforcement official, told NYT on condition of anonymity because he was not allowed to speak publicly.

“I know prosecutors in Arizona, Virginia, Minnesota,” added Carla Freedman, an assistant district attorney in New York who in 2013 prosecuted a Chinese drug trafficking ring.  “We’re seeing cases nationwide and ground zero always seems to be China.”

Online dispensers in China have also been linked to selling synthetic drugs that have been blamed for recent fatalities in the U.S.

Illegal synthetic drugs can easily be acquired from online retailers in China, according to The Times.

“In a country that has perfected the art of Internet censorship, the open online drug market is just the most blatant example of what international law enforcement officials say is China’s reluctance to take action as it has emerged as a major player in the global supply chain for synthetic drugs,” notes the article.

“China’s chemical factories and drug traffickers have exploited this opportunity, turning the nation into a leading producer and exporter of synthetic drugs, including methamphetamine, as well as the compounds used to manufacture them, according to seizure and trafficking route data compiled by American and international law enforcement agencies,” it adds.

The DEA reportedly identified China as the origin of most of the ingredients that Mexican drug traffickers use to manufacture methamphetamine.

“As governments around the world have stepped up regulation of these so-called precursor chemicals, the Mexican cartels have increasingly turned to Chinese chemical factories,” reports NYT.

Moreover, it adds that “on guidechem.com, more than 150 Chinese companies sell alpha-PVP, also known as flakka, a dangerous stimulant that is illegal in the United States but not in China, and was blamed for 18 recent deaths in one Florida county.”

Qijiayuan, an e-commerce portal that sells air-conditioners and trampolines, also sells an illegal hallucinogen known as spice, which has been linked to a rise in U.S. emergency room visits in April.

Although it is prohibited in China, the Nanjing Takanobu Chemical Company readily sells the stimulant mephedrone, known as “bath salts,” for $1,400 per pound.

“While China says it has made thousands of arrests and ‘joined hands’ with foreign law enforcement agencies, officials from several countries say Chinese authorities have shown little interest in seriously combating what they see as the drug problems of other countries,” mentions The Times article.

“They just didn’t see what was in it for them to look into their own industries exporting these chemicals,” Jorge Guajardo, who served as Mexico’s ambassador to China from from 2007 to 2013, told NYT.

Guajardo added that his efforts to stem the flow of illegal chemicals from China to Mexico failed.

“Instead, he said, Chinese officials said the problem was best handled by Mexican customs agents or claimed that Mexico’s written requests for assistance had used the incorrect typeface or were improperly translated into Chinese,” notes The Times.

“In all my time there, the Chinese never showed any willingness to cooperate on stemming the flow of precursors into Mexico,” declared Guajardo.

Chinese officials claim that their government is committed to stemming the flow of illegal drugs.

“We aim to help and support other countries in any way we can,” reportedly said Liu Yuejin, the assistant minister of public security.

“In response to faxed questions, the Chinese Foreign Ministry denied any problems in law enforcement cooperation with Mexico,” notes The Times.

According to a United Nations report released in May, the police in China raided an estimated 390 meth labs, more than in any other nation in the region.

“These manufacturers have flourished in part because the country’s huge chemical industry is weakly regulated and poorly monitored, officials say, making it easy for criminal syndicates to divert chemicals with legitimate uses in making medicine, fertilizer and pesticides into the production of new and dangerous drugs,” reports The Times.

“The labs have also figured out how to stay one step ahead of laws banning illicit synthetic drugs simply by tweaking a few molecules, creating new and not-yet-illegal drugs,” it continues.