NATO warplanes killed at least 20 militants on Wednesday during a major operation to drive out Taliban rebels from villages near the southern Afghan city of Kandahar, the defence ministry said. "A group of enemies of the people was targeted by NATO air force in Ta-been village in Arghandab (district). Based on information received, 20 local and foreign terrorists were killed," the ministry said in a statement. Afghan soldiers backed by Canadian NATO troops launched an operation early Wednesday in Arghandab, days after hundreds of Taliban militants massed in the district.