More than 30 Taliban fighters and four policemen were killed in a series of clashes, airstrikes and bombings in Afghanistan, officials said Wednesday. A group of Taliban fighters attacked a police checkpoint in Nad Ali district of southern Helmand province on Tuesday, sparking a clash that killed 18 militants, a provincial police chief Mohammad Hussein Andiwal said. The militants attacked the officers guarding a government compound in the district before being repelled by police, Andiwal said. There were no casualties among Afghan troops, he said. Insurgents have attacked the same checkpoint many times in the past, and the authorities had reinforced their positions, Andiwal said. US-led coalition troops, meanwhile, clashed and called in airstrikes against militants in the same province, killing more than a dozen insurgents, the coalition said in a statement.