BEIJING — Top American and Chinese enforcement officials are negotiating how to fight the rampant trade in synthetic drugs manufactured here and blamed for a deadly wave of spiked opioids in the United States.

A 14-member delegation from the US Drug Enforcement Agency, led by Deputy Chief of Operations Lizette Yrizarry, spent a week in China in August, meeting with Narcotics Control Bureau and Public Security Bureau officials, DEA officials said.

The DEA agreed to help train Chinese drug cops how to investigate money laundering and financial irregularities related to the trade in fentanyl and related synthetic opioids, many of which remain legal in China. China's narcotics officials in turn agreed to possibly share evidence and tips with US officials on the trade, which could lead to joint operations.

The talks also touched on emerging synthetic drugs — as Chinese chemical factories evolve to stay ahead of enforcement efforts — the export of precursor ingredients and pill presses used to make drugs, and smuggling via freight forwarding companies.

Fentanyl, a pain drug that is 50 to 100 times stronger than morphine, has been linked to hundreds of overdoses and deaths in the United States this year alone, including that of music icon Prince. It is mixed into heroin and made to appear like less potent pain pills, and overdose victims often have no idea that they're taking fentanyl.

Most of the illicit fentanyl found in street drugs originates in China, according to the DEA and United Nations narcotics monitors, reaching American users through direct shipments arranged over the internet and the export of precursor chemicals and pill presses to cartels in Mexico and drug dealers in the United States and Canada.

Russ Baer, spokesman for the DEA, said the dialogue with Beijing comes at a critical time. "If we are really to have a serious exchange with China, and we were to limit the exports of fentanyl and fentanyl precursor compounds and pill presses that are tableting these counterfeit medications, that would be huge," said Baer. "That would be … one very important step in tackling America's addiction crisis."

The two countries released an opaque joint statement during the G-20 meeting in China two weeks ago, the product of weeks of difficult negotations. "China will pay special attention to the substances exported to and controlled in the United States that are not controlled in China, and will fully explore the possibility of further scheduling of these substances," the statement read in part.

While Chinese officials resent being blamed for the US opioid crisis, Chinese and US government officials said the statement shows China is willing to take further steps to interrupt the illicit opioid trade.

Fentanyl pills. AP/Cuyahoga County Medical Examiner's Office

"Research chemicals" for sale

Drug dealers operate out in the open online in China, offering fentanyl and other synthetic substances for sale in unrestricted quantities, nearly a year after China banned more than 100 synthetic drugs.

STAT scoured the internet for fentanyl ads, contacting more than 40 companies advertising fentanyl and other "research chemicals" for sale. Only two replied, but one marketing manager who called herself Alisha explained in great detail during an online chat how the business works.

The industry operates under the same basic framework as any other foreign trading company, the young woman said, and offered advice on entering the business — which is under pressure but not illegal in China. She refused to meet but said the company, based in Hebei province north of Beijing, could offer a small, free sample. For the rest, Alisha said this is a seller's market and the profits are large.

"I have five years experience in hardware," she wrote. "You will find out that for this industry, customers are not necessarily our god. My boss said when they first began in this industry, they won't deal with customers who bargain. More people are entering this industry but still less than those in common products. Only my boss knows the source of goods."

Along with a dozen other online fentanyl purveyors, Alisha's company lists its factory address in Xingtai, a gritty industrial town 250 miles southwest of Beijing in Hebei province. But a trip to Xingtai revealed that all the companies use fake addresses in their online profiles, with several listing a high-end residential and commercial development at the center of town as their headquarters. The companies do exist and present a legitimate face online, but they are hidden behind layers of false names and addresses.

Xingtai could well be a production center for synthetic opioids. A former chemical manufacturing stronghold with a lagging economy, it has production know-how and a need for jobs. And China's massive chemical industry — along with India, it makes a majority of the world's pharmaceutical ingredients — has long been riddled with corruption and quality and regulatory issues, resulting in a well-documented and sometimes deadly counterfeiting problem.

Abid Katib/Getty Images

Stopping the flow of synthetic drugs

So why has China been slow to act on US pleas to stamp out the trade that has proven deadly for Americans and Canadians and embarrassing to Beijing? DEA officials said that China's image-conscious government resents being blamed for America's opioid addiction problem and wants more credit for what it's already done — namely its October ban on consumer sales of 116 chemicals, including 19 fentanyl analogues. Although Chinese drug labs rapidly circumvented the rules by developing a hybrid fentanyl, the dangerous made-in-China stimulant "flakka" has all but disappeared from the United States.

Moreover, China is overwhelmed and wants US help with its own drug problems. Chinese officials have documented a troubling rise in addictions to methamphetamine and ketamine — an anesthetic drug popular with recreational users in Asia. In June 2015, the Ministry of Public Security took several unprecedented steps in its domestic war on drugs. It revealed the country has 14 million drug users, most of whom are hooked on meth, ketamine, or heroin. But heroin is losing its appeal in favor of the synthetics, meth and ketamine.

Shen Tingting, a human rights activist in Beijing, said China's current drug-control efforts are almost entirely focused on heroin, while the use of synthetic drugs is rising quickly.

"In the past decades, the Chinese government has been putting a lot of efforts to educate the harm of heroin, so heroin has really bad image and scare the young generation," Shen said. "Many people are not aware of the harm that synthetic drugs can bring."

Martin Raithelhuber, illicit synthetic drugs expert with the United Nations Office on Drugs and Crime, said stopping the flood of synthetic opioids is complex.

"Even if you could stop all manufacture of these substances in China today, there is a chance that someone in the US or Canada could pick up the manufacturing," he said.

To make any progress, Raithelhuber said, the US and China need to quit faulting one another about drug addiction on one side and lack of regulations on the other, and work toward solutions.

"We have to come out of this chicken-and-egg mentality and recognize the responsibility each part has," he said. "It's a common problem and a common responsibility. Blaming one another does not help."