Hospitals and health ministries in 40 countries have been targeted by scammers offering vaccines against Covid-19 that turn out to be non-existent.
Interpol issued an alert to its 194 members which said the fraudsters posed as vaccine manufacturers and used fake social media accounts and websites.
In at least 60 cases, buyers received spurious offers to purchase vaccines that were approved in their country.
It is the latest in a series of Covid-related swindles which have led to companies being duped into buying fake masks and bogus vaccine passports traded online.
Real vaccines are distributed by healthcare officials and no legitimate shots are available for sale online.
Interpol said fraudsters targeted health workers and officials through their personal and professional email accounts and sometimes by phone.
They tried to impersonate drug makers or government agencies and offered vaccines for sale which would never arrive.
“Even when a fraud fails, it is important that it is reported to the police so that potential links can be identified,” Interpol chief Jurgen Stock said.
“With the ongoing pandemic and efforts of countries to safely and quickly vaccinate their citizens, it is vital that the roll-out process is protected from manufacture to delivery.”
The agency said criminals had “exploited every stage of the pandemic” with offers of fake goods and cyber attacks on healthcare systems.
Police in Europe last week charged 23 people over a swindle in which companies were sold fake protective equipment such as face masks.
The fraudsters were estimated to have made €1 million ($1.2m) in proceeds which were laundered through Romanian bank accounts.