KABUL, Afghanistan (CNN) -- Intense fighting between troops and militants has unfolded over the past few days in a hotbed of insurgents and narcotics trafficking in southern Afghanistan, NATO said in a statement Wednesday.
The International Security Assistance Force (ISAF) said the fighting is in Marjah, a region in Helmand province 20 kilometers (more than 12 miles) southwest of the provincial capital of Lashkar Gah.
Recent successful operations against the insurgents in the area have prompted a buildup of militant forces and a spike in militant activity, said ISAF, which noted that Afghan security forces backed by international troops "recently seized a significant quantity of narcotics in the Marjah region."
ISAF said there is a "clear link" in Marjah "between the narcotics trade, corruption and the financing of the insurgency." It said the narcotics trade helps pay for weapons, bombs, and suicide bombers.
"Importantly, the influx of foreign insurgents and the end of the poppy harvest always contributes to an annual increase in the number of incidents in this region," ISAF said. Fighters from Balochistan -- the southwestern Pakistani province that borders southern Afghanistan -- are among the foreign fighters.
"Troops operate throughout the year and are fully prepared for any rise in seasonal violence, especially given the increase in U.S. forces moving into the area," ISAF said.
Making note of the importance of preventing civilian casualties during the fighting, ISAF said "it is vital that innocent civilians separate themselves" from militants.
"In doing so they will not be mistaken for insurgents or caught up amongst insurgents whose cowardly tactics see them hiding in the civilian population, thereby causing the loss of innocent lives," ISAF said.
In another statement, ISAF said Tuesday airstrikes near Lashkar Gah caused civilian casualties when they targeted insurgents who they learned later were "using civilians as human shields." The incident occurred south of Lashkar Gah in Nawa.
"If this information had been known by ISAF troops, no ordnance would have been used. Tragically, it is believed that eight civilians were killed as a result of the airstrike. This terrible incident again shows the insurgents' blatant disregard for the lives of Afghan people," ISAF said.