Afghan officials say at least 12 policemen have been killed or wounded in two separate Taliban attacks on checkpoints.

In one of the assaults, authorities said six policemen were killed in an early morning gunfight Wednesday with insurgents in the Qarabagh district 120 kilometers southwest of Kabul.

On Sunday, three police were killed in a similar insurgent attack on their checkpoint in the same district.

In the second incident Wednesday, at least six policemen were killed or wounded when a suicide bomber blew himself up at a checkpoint in Afghanistan's eastern Ghazni province. Clashes erupted between insurgents and police after the bombing.

Earlier, on Tuesday, Afghan officials say a suicide bomber blew himself up outside the offices of the central Parwan province's governor, killing two people and wounding two others. Officials said the governor escaped unharmed. The Taliban also claimed responsibility for the Parwan suicide bombing.

In other violence Tuesday, NATO said one of its soldiers was killed following a bomb blast in the south.

The Taliban has stepped up its attacks on government officials and Afghan and international troops in recent months.