Suspected leftist rebels in Colombia have killed at least a dozen coca growers in the northwestern part of the country.

A local official says members of the Revolutionary Armed Forces of Colombia, or FARC, killed 11 men and one woman during an attack Wednesday near Puerto Valdivia.

The FARC relies on coca, which is used to make cocaine, for much of its funding. It often kills peasants who refuse to cooperate or sell their product to rightwing paramilitaries.

The FARC and a smaller leftist rebel group are locked in a long-running war against the government and rightist paramilitaries that leaves thousands of people dead each year.

Some information for this report provided by Reuters and AP.