The International Narcotics Control Board (INCB) said in its annual report that abuse of prescription drugs has become a major problem not just in the U.S. but also in Canada and Mexico, the BBC reported March 1.

The INCB estimated that 10 million illegal shipments of prescription drugs entered the U.S. -- where prescription drug abuse now equals the problem of illicit drug abuse -- each year.

The United Nations agency said that the Internet has become a major conduit for shady sales of prescription drugs, and urged all countries to screen incoming and outgoing mail.

The INCB report, which looked at drug trends around the world, also concluded that drug-crop replacement strategies have not been effective, that cocaine production is rising in South America, and that Afghanistan is now producing 87 percent of the world's opium.

The agency also said that more people are using marijuana in Africa (34 million) than in the European Union (30 million).