BEIJING (Reuters) - China's top prosecutor urged law enforcement officials across the country on Friday to focus efforts on combating drug trafficking, capping a week in which Beijing and Washington announced a rare joint counternarcotics investigation.

The Supreme People's Procuratorate published "six typical cases," involving actions ranging from postal fraud to medical professionals selling illicit drugs on the side, and clarified the legal application standards to handle such cases.

The prosecutor said in a statement that the release was meant to show its "determination and attitude to intensify efforts to crack down on related crimes, while hoping that this batch of typical cases will serve as a warning to the society."

The United States and China held high-level counternarcotics talks on Thursday following a breakthrough in bilateral cooperation this week in which both sides went after a major drug-linked money laundering operation.

The United States, where fentanyl abuse has been a major cause of death, has pushed China for deeper law enforcement cooperation, including tackling illicit finance and further controls on the chemicals that can be used to make fentanyl.

These chemicals are often shipped to the U.S. and other destinations from China using mail packages that have unverifiable addresses or are mislabeled, experts say. The U.S. Postal Service has for years struggled with the problem.

One of the examples highlighted in the prosecutor's note on Friday involved a case of a Chinese buyer, surnamed Yan, purchasing date-rape drug triazolam from overseas and then selling it in China by mail using mislabeled packaging.

As a result, "the procuratorate issued a procuratorial suggestion to the postal administration department...urging the regulatory department to fulfill its main responsibility and perform its duties conscientiously."

The postal administration then "urged the company to make timely rectifications," the prosecutor said.

The note said "the procuratorate invited nearly 100 couriers and college students to attend the trial, focusing on the new characteristics and new forms of new drug cases to carry out anti-drug law publicity."

Postal fraud was briefly mentioned in the opening remarks by Rahul Gupta, director of the White House Office of National Drug Control Policy, who on Thursday held talks in Beijing with China's minister of public security, Wang Xiaohong.

Gupta said it was among the "areas where we're both being negatively impacted," listing it alongside illicit finance, "illegal drug trafficking and use, and the emergence of new and more dangerous drugs."

(Reporting by Antoni Slodkowski; additional reporting by Beijing newsroom, Editing by Timothy Heritage)

By Antoni Slodkowski