A senior government official and his security guard have been shot dead in Afghanistan's southern Helmand province.

Local government officials said Mohammad Anwar Khan, district administrative chief of Nad-e-Ali district, was shot dead on Tuesday.

Omar Zwak, a spokesman for the provincial governor of Helmand, said Khan was killed in the ambush and that six police officers had been wounded in the attack.

The Taliban have a strong presence in Nad-e-Ali and use the district as a base to launch attacks elsewhere in the province.

No one immediately claimed responsibility for the killings, but Taliban fighters have increased their attacks against Afghan government officials across the country ahead of most foreign troops withdrawing at the end of the year.

'Sticky bomb'

Earlier on Tuesday, Taliban fighters killed six Afghan police officers, officials said, one of a string of attacks on local security forces, highlighting the challenge they face as NATO troops withdraw.

The attack on a police post in Logar province, south of Kabul, came a day after a convoy was ambushed in the north in an attack that killed 22 policemen.

"A group of Taliban attacked a local police post in Baraki Barak district early in the morning and killed six police," district chief Mohammad Rahim Amin told the AFP news agency.

Din Mohammad Darwish, the provincial governor's spokesman, confirmed the attack and said the incident was under investigation.

Also on Tuesday, a "sticky bomb" attached to a car in Kabul killed two civilians, and injured three others, the interior ministry said in a statement.

The Taliban also claimed responsibility for that attack, saying they targeted an intelligence agency car. 

Lack of proper weapons

There have been persistent concerns about whether Afghan forces will have the wherewithal to subdue the Taliban without the backing of US-led NATO forces.

Interior Minister Omar Daudzai on Tuesday told a gathering of security commanders that a lack of proper weapons was hampering the police and causing heavy casualties.

"Police do not have proper arms. The enemies attack police posts with heavy guns while police defend with AK-47s," he said.

The US military estimated this month that 7,000 to 9,000 Afghan police or troops had been killed or wounded so far this year.

Source: Al Jazeera and agencies