An Afghan boy collects resin from poppies in an opium poppy field in Arghandab district of Kandahar province, south of Kabul, Afghanistan (2008 file photo)

The United States says international drug trafficking continues to threaten U.S. security, highlighting drug problems in countries such as Afghanistan and Mexico.

The State Department released its annual International Narcotics Control Strategy Report Friday.

The report identified 20 countries, including Afghanistan, Mexico, Nigeria and Pakistan, as "major" producers and transit points for illegal drugs. Of those, Bolivia, Burma and Venezuela were said to have "failed demonstrably" to adhere to international counter-narcotics agreements.

The report says Afghanistan slashed opium poppy cultivation by 19 percent in 2008 after two years of record highs. But it says the narcotics industry continues to fund the Taliban insurgency and threatens efforts to establish security in the country.

In Mexico, the report says the government has made headway in its fight against drug cartels, but the crackdown has led to more violence as gangs battle each other for diminishing profits.

At a briefing Friday, a State Department spokesman said Mexico's government is taking "courageous" steps to confront the drug problem, and is working in cooperation with the United States.

Some information for this report was provided by AP and Reuters.