Criminal organisations have introduced fake anti-cancer drugs into the market, said an Italian official.

Experts fear that the fake drugs could be inefficient or even deadly, and specialist police officials from the Nuclei Antisofisticazioni e Sanità Carabinieri as well as medical watchdog Agencia Italiana fel Farmaco (AIFA) are investigating the racket.

"Organised crime is certainly involved; there's a central structure apparently based in Italy that commissions thefts of medicines in hospitals," Domenico Di Giorgio, director for the prevention of counterfeiting at the AIFA told the Wall Street Journal.

Sources told the paper that medicines had been stolen from hospitals, and that the Naples-based Camorra mafia, eastern European gangs and a Russian citizen living in Cyprus were believed to be involved.

In mid-April, The European Medicines Agency warned that tainted phials of the Roche breast cancer drug Herceptin had surfaced in Finland, Germany and the UK after being stolen in Italy, with batches diluted to render it ineffective.

Later, the agency reported that batches of lung cancer drug Alimta and Remicade, which is used to treat rheumatoid arthritis, had also been taken.