The casualties figures were revealed on Friday amid concern that fighters have been aided by a disarmament drive.
Master Sergeant Cindy Beam told AFP the clashes were part of a joint operation with Afghan forces in the vicinity of Daychopan in southern Zabul province.
"We have also confirmed 17 enemy KIAs (killed in action)," she said.
"Coalition forces are reporting that three US marines received minor wounds in this contact and returned to duty."
More than 100 Afghan soldiers, supported by dozens of US-led troops and helicopters, launched the operation on Wednesday in Mianeshin district, some 140km north of the main southern city of Kandahar, Kandahar provincial government spokesman Khalid Pashtun said.
Pashtun said 13 fighters were killed and eight captured in the operation.
Afghan forces were Friday pursuing around 50 suspected Taliban, Pashtun said.
Several foreigners have been
killed in recent months
"The government troops are chasing them into the nearby mountains," he said.
Uruzgan police commander Shah Muhammad Khan said four suspected fighters were killed in clashes with pro-government militias in Zabul. Khan's police had travelled to neighbouring Zabul to assist in the operation, he said.
"Four Taliban were killed in Daychopan district," he added.
Khan said Taliban fighters had increased their activities in the region, partly in response to a weakening of pro-government forces as a result of an ongoing nationwide disarmament, demobilisation and reintegration (DDR) drive.
More than 1445 officers and soldiers have been disarmed under the main phase of the programme which has targeted Kabul, Kandahar, northern Kunduz and south-eastern Gardez.
Nationally some 7630 people have been disarmed, according to the latest UN figures.
"DDR can be very effective if there is no fear of Taliban in the region," Khan said.
"(But) I would like to be clear that we still need AMF (Afghan Militia Forces) to tackle the Taliban," he said.
Regional commanders, who control much of Afghanistan, have previously voiced concerns that disarming their troops could give Taliban and other groups an advantage.
The disarmament programme is
said to be helping the Taliban
Southern and south-eastern Afghanistan have been hit by a wave of attacks blamed on resurgent Taliban fighters after the government was forced out of power by a US-led military offensive in late 2001.
Kandahar, some 480km south of Kabul, and the neighbouring southern provinces of Uruzgan, Zabul and Helmand have been the scene of several bloody attacks on government and US-led troops in recent weeks.
All provinces are former strongholds of the Taliban.
Four US Special Operations soldiers were killed last week when their vehicle hit a landmine near Qalat, the capital of Zabul, bringing to six the number of US soldiers killed in the past month.
Nine Taliban rebels were killed early last week in clashes involving pro-government and US-led troops in Zabul, according to US and Afghan military officials.
Less then two weeks ago, government troops backed by US aircraft killed 20 suspected Taliban fighters in Kandahar's Arghistan district.
Since early May, dozens of combatants on both sides have died in fighting, while eight aid workers, five of them foreign nationals, have also been killed in violence.