Officials say insurgents have attacked several army checkpoints in eastern and southern Afghanistan, killing at least four troops and wounding several people.

No one has claimed responsibility for the attacks, which happened Sunday, but the Taliban have stepped up assaults on Afghan and NATO forces ahead of the pullout of most foreign combat troops by the end of the year.

Defense ministry spokesman Gen. Mohammad Zahir Azimi said on Monday that the four soldiers died in an attack in the eastern province of Logar, in the Charkh district. He says scores of insurgents were killed in a subsequent airstrike there.

In southern Uruzgan province, spokesman Dost Mohammad Nayab says insurgents attacked police checkpoints in Gezab district. He says Afghan forces suffered no casualties but that four attackers were killed.