The battle in southern Kandahar province erupted during a police search operation, Zhari district police chief Ghulam Rasoul Aka told AFP.
"Four Taliban were killed. Two Taliban and one policeman were wounded in the four-hour exchange of fire," he said.
Police meanwhile reported that Taliban fighters ambushed a convoy supplying logistics and goods to a US base in the south-east of the country late on Friday, killing two Pakistani drivers and wounding an Afghan.
The attackers opened fire on the two trucks from both sides of the road in a mountainous area of Khost province late on Friday, the provincial police chief told AFP.
"Two Pakistani co-drivers were killed and one Afghan driver was wounded in an enemy attack on non-military trucks hired to supply goods for Americans," General Abdul Hanan Raufi told AFP.
Raufi said the attack was carried out by Taliban insurgents who fled immediately afterwards. Police were searching for the killers, he said.
There have been several such attacks on convoys supplying bases for the 40,000 troops in Afghanistan, about half of whom are Americans.
Taliban militants are using several tactics in their insurgency, with most of the violence targeted at Afghan and foreign troops and civilians who work with them or the government, including school teachers and mullahs.
The fighters also used suicide and roadside bombings, and have met with strong retaliation from foreign and Afghan forces.
More than 3,000 people have been killed in the violence, about two-thirds of them rebels.

Copyright AFP (Agence France-Presse), 2006