Afghan and NATO troops targeted a group of Taliban fighters in southern Afghanistan, killing 17 militants and wounding six others, the Defense Ministry said Monday.

Four police were killed separately in a militant ambush in central Ghazni province, a provincial official said.

The joint force clashed Sunday with militants in the Marjah district of Helmand province, the ministry said in a statement. The troops seized weapons and ammunition belonging to the militants and 132 pounds of drugs after the clash, it said.

Southern Afghanistan is the center of the Taliban-led insurgency that this year has claimed more than 2,700 lives, according to an Associated Press tally of figures provided by Afghan and Western officials.

Helmand province is also the world's largest producer of opium poppies, the main ingredient in heroin. Western officials say some of the proceeds from the multibillion dollar trade fund the Taliban. Government officials are also believed to be involved in the illicit trade.

Also Sunday, militants ambushed a two-vehicle police convoy in Ghazni's Zana Khan district, killing four officers and wounding seven, said Sayed Ismail Jahangir, a spokesman for the provincial governor.

Separately, the U.S.-led coalition said its troops killed several militants and captured one they had sought in Ghazni's Waghaz district on Sunday. The troops were searching for a militant wanted in connection with planting roadside bombs, it said in a statement Monday. It did not specify the number of militants killed.

On Monday morning, a pair of Taliban fighters died when a mine they were planting exploded prematurely in the Spin Boldak district of Kandahar province in the country's south, said Gen. Abdul Raziq, a border security commander.