FILE PHOTO - A view shows the U.S. Food and Drug Administration (FDA) headquarters in Silver Spring, Maryland August 14, 2012. REUTERS/Jason Reed/File Photo

(Reuters) - The U.S. Food and Drug Administration and the Drug Enforcement Administration (DEA) jointly issued warning letters to four online networks for illegally marketing unapproved and misbranded versions of opioid medicines, the agencies said.

The networks which were issued the warning letters on Monday are Divyata, Euphoria Healthcare Pvt Ltd, JCM Dropship and Meds4U, which operate a total of 10 websites.

The move comes at a time when health regulators in the country are combating the rising use of opioids, which were responsible for 47,600 overdose deaths in the United States in 2017.

Misbranded drugs are those that fail to bear adequate directions for their intended use, the FDA said.

The networks also violated the Controlled Substances Act by not registering the online pharmacies with the DEA despite advertising for the sale of opioids, the agencies said. (bit.ly/2nb9xtA)

In case the online networks fail to take corrective action within 15 working days, the websites’ domain name registrars may be informed, the agencies said.

In June last year, the FDA issued warning letters to nine other online networks operating a total of 53 websites, to stop illegally marketing unapproved versions of opioid medications. (reut.rs/2nScPlN)