The dead included two Chechens and three Pakistanis, the army officer said on Tuesday.
AFP earlier reported eight killed and 16 arrested after a gun battle between Afghan government troops supported by US forces and Taliban fighters in southeastern Afghanistan.
Afghan officials said the fighting took place on Monday after rebels clashed with military forces in Zabul's Deh Chopan district.
Defence Ministry spokesman General Muhammad Zahir Azimi confirmed that "eight Taliban were killed and 16 others were arrested", adding that four of the captured men were wounded.
Azimi and the local official said the US-led coalition, which has 18,000 troops in Afghanistan helping to root out remnants of the Taliban, provided air support for the war-battered country's fledgling national army.
US military spokeswoman Lieutenant Cindy Moore confirmed that coalition forces supported the battle on the ground and from the air.
Remnants of the Taliban continue
to harass Afghan and US forces
"Coalition forces did engage insurgents on the ground and provided air support," she said, but had no details on the number of Taliban casualties. She said coalition forces did not suffer any injuries.
Zabul province, which lies on the rugged Afghan-Pakistani border, is one of the most insurgency-hit regions in Afghanistan where remnants of the ousted Taliban still carry out attacks on foreign and government forces.
In a separate development, the US has sent home 17 Guantanamo prisoners to Afghanistan and another to Turkey.
Some of the Afghans said upon arrival in Kabul on Tuesday they had been mistreated by their American prison guards.
Abd al-Rahman, who appeared to be in his mid-30s and was among three men allowed to speak to reporters after being handed over to Afghan authorities, said: "They used extreme type of tyranny against us."
"They used extreme type of tyranny against us"
freed Guantanamo detainee
Some said they had been in detention since the 2001 fall of Afghanistan's former Taliban rulers in a US-led invasion.
The 18 who were released in the largest single exodus from the US naval base at Guantanamo Bay, Cuba, since last September were among 38 detainees who the Pentagon had decided no longer were considered enemy combatants.
The US still holds roughly 520
prisoners at Guantanamo base
Maj Michael Shavers, a Pentagon spokesman, said another 15 detainees who also no longer were classified as enemy combatants remained at Guantanamo awaiting transfer to their home countries.
Five others previously were released.
The US still holds approximately 520 prisoners at Guantanamo after freeing 167 to their home countries and sending 65 more to their home governments for continued detention, the Pentagon said. Many detainees have been held for more than three years.
Human-rights activists have accused the US of condemning Guantanamo prisoners to indefinite detention in a "legal black hole," and note that some former detainees have said they were tortured by US personnel at the base.