It gave no statistics on online drug sales, which are normally conducted on so-called "darknets", or anonymous computer networks.
The report, compiled by the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) and Europol, the pan-European police agency, said increased globalisation and communication technology made it harder to track drug routes.
"Practically any type of drug can be bought on the Internet," Europol director Rob Wainwright told a briefing. "The consumers may feel that it is 'cleaner' to buy drugs without any direct contact with the drug dealer."
These drugs are being moved through legitimate forms of commercial transportation containers, aircraft and postal services, all making the drugs harder to intercept.
EMCDDA director Wolfgang Goetz said drug users' behaviour was also changing.
"Patterns of drug use have become more fluid, with consumers often using multiple substances or substituting one drug for another," Goetz said.
Northwest Europe a major concern
Europol's Wainwright said drug trafficking was the main activity of organised crime groups, providing funding for other criminal activity.
The report pinpointed northwest Europe Britain, the Netherlands, Belgium and northern France as an area where organised crime is high, partly because of its many transport hubs, and Wainwright said the region's status as a final destination for cocaine and heroin, as well as people trafficking and illegal immigration, made it a major concern.
The report recommended that the European Union work to target high-value crime groups, develop intelligence on the geographic relocation of potential criminals, interrupt money flows and create barriers to drug sales on the Internet.
EU Home Affairs Commissioner Cecilia Malmstrom said ministers from the 27 member states would study the report for possible policy changes and action across the European Union.
"We need to keep pace with these new developments and adapt our policies and responses to this reality," Malmstrom said. "National measures, however robust, will simply not be sufficient if implemented in isolation."
The European Union is an increasingly important producer of synthetic drugs and cannabis, with mobile production units making it easy for synthetic drugs to be concealed during manufacturing.
"As with synthetic drugs, there has been a trend towards producing the drug near to its intended consumers," Goetz said. "This will be a growing trend in the future."
The report estimated 2,500 tonnes of cannabis are consumed each year in the European Union and Norway, with a retail value of 18-30 billion euros.
Malmstrom said no European-wide legalisation of cannabis is on the Commission's agenda.
© Thomson Reuters 2013