It was not immediately clear why there was a discrepancy in the number of reported casualties, which was impossible to confirm independently because the scene of the fighting is remote and insecure.
A coalition statement said the fighting started after a joint Afghan-coalition patrol was attacked in Uruzgan province's Tirin Kot district Tuesday evening. The troops beat back the assault and forced the militants to retreat.
Beside the troops and police killed, six Afghan soldiers and three police were wounded, the statement said.
The military commander for southern Afghanistan, Gen. Rehmatullah Raufi, said four Afghan soldiers had died and that the bodies of about 60 militants were recovered.
He said coalition airstrikes were called in toward the end of the battle.
Maj. Scott Lundy, a coalition spokesman, confirmed that the coalition provided air support.
The fighting began in a small village in Tirin Kot district before the militants fled higher into the mountains, Raufi said. It was there that airstrikes bombed Taliban positions, he said.
In the past year, Uruzgan has been the site of some of the heaviest fighting in Afghanistan, but militants suffered high losses in multiple battles with coalition forces, and the violence there has subsided in recent months.
Last Friday, a U.S. soldier was killed and seven wounded in a battle in southern Uruzgan that also saw 20 Taliban militants killed.
Militants have stepped up attacks in the last several months, particularly in Afghanistan's southern and eastern regions near its border with Pakistan. Thousands more NATO forces are scheduled to move into the areas in the next few months, during summer in the region.
Meanwhile, the U.S. military on Wednesday defended an airstrike on a southern Afghan village that killed at least 16 civilians, saying its troops were being fired on and they had the right to defend themselves.
U.S. military spokesman Col. Tom Collins also apologized to the victims' families, saying "we never wanted this to happen." He said the coalition has offered assistance to the families, but didn't disclose details.
"The ultimate cause of why civilians were injured and killed is because the Taliban knowingly, willfully chose to occupy homes of these people. We do everything we can to prevent killing civilians," he told reporters in Kabul.
Collins said the troops did not know there were civilians in the homes overnight Sunday when the U.S. military called in Air Force A-10 Warthogs to strafe the buildings with large-caliber bullets.
The military has confirmed the deaths of 20 militants in the assault on the village of Azizi and believes up to 60 more may also have died. Collins said some unidentified local Taliban leaders may be among the dead.
The airstrike was one of the deadliest since the American-led invasion in 2001, and Afghan President Hamid Karzai has , the second time in five weeks the leader has complained about civilian deaths from airstrikes.
Collins said the military estimate of the number of civilian deaths was the same as that of Asadullah Khalid, the governor of Kandahar, who has said at least 16 died.
The U.S. airstrike and the Taliban's tactic of hiding behind civilians drew criticism from human rights advocates.
"Taliban insurgent forces who take shelter in a civilian area knowing that it's going to draw hostile fire are violating international law," said Sam Zarifi, head of New York-based Human Rights Watch's Asia division.