UNITED STATES (REUTERS) - US and Afghan forces have launched joint attacks on Taleban opium factories to try to curb the insurgent group's economic lifeline, the commander of US forces in Afghanistan said on Monday (Nov 20).

US Army General John Nicholson showed videos at a press conference of targeted aerial strikes against what he described as Taleban drug factories.

"To some extent, it is fair to say that this movement has evolved into a narco-insurgency," Nicholson said. He was speaking via satellite from his headquarters in Kabul to reporters based in Washington.

Opium production in Afghanistan reached record highs this year, up 87 per cent on last year, the United Nations said last week.

The UN Office on Drugs and Crime (UNODC) said output of opium made from poppy seeds in Afghanistan, the world's main source of heroin, stands at around 9,000 metric tons this year.

UNODC has warned in the past that Kabul's weakening grip on security was contributing to a collapse in eradication efforts.

Nearly half of Afghan opium is processed, or refined into morphine or heroin, before it is trafficked out of the country, according to US and Afghan officials.

The four-star general showed one video of an F-22 fighter jet dropping 250-pound bombs on two buildings, emphasising that a nearby third building was left unscathed.

US troops have long been accused of causing unnecessary collateral damage and civilian deaths. The United States says it takes every precaution to avoid civilian casualties.

The United Nations said at least 10 civilians may have been killed by a strike in Kunduz earlier this month, contradicting a US investigation that found no civilian deaths.