Taliban fighters have attacked a NATO convoy in western Afghanistan, killing at least 10 private security guards and injuring several, officials said.

A government spokesman told Al Jazeera that the NATO logistics convoy came under attack in Farah province’s Bakwa district on Thursday. At least ten vehicles were set on fire.

In July, 31 workers from a demining agency were abducted in Bakwa, six of whom were killed and the rest released.

The attacks come as Afghanistan prepares to assume security control ahead of the 2014 withdrawal date for the US-led NATO combat troops.

In the first round of “security transition”, seven areas have been handed over to Afghan forces already.

Hamid Karzai, the Afghan president, is expected to announce 17 other provinces as part of the the second phase.

‘Civilians killed’

Meanwhile, Karzai accused NATO-led international forces of killing up to seven civilians, most of them children, in an air strike in the south of the country late on Wednesday.

The incident happened in Zhari district of Kandahar province, a traditional Taliban stronghold where NATO-led International Security Assistance Force (ISAF) troops claim significant progress in recent months.

The Kandahar governor’s office said that the air strike was aimed against armed men who were planting mines, but they then fled into a village, where ISAF forces pursued them and struck.

A spokesman for the NATO-led International Security Assistance Force in Kabul said he was aware of reports of civilian casualties in Kandahar, adding that a joint assessment team was going to the site.

The issue of civilian casualties in air strikes is highly sensitive in Afghanistan and has fuelled tensions between Karzai and his Western backers.

Karzai’s office issued a statement saying he “strongly condemned” the strike, which it said killed seven people including six children, as well as injuring two young girls. The president has also tasked a team with investigating the incident.

The governor of Zhari district Niaz Mohammad Sarhadi said that the strike was aimed at Taliban fighters planting roadside mines in the area but missed its target and hit residential areas nearby.

But the governor’s office in Kandahar gave a slightly different explanation.

It said that two insurgents had been killed in an air strike, “while the three remaining fled and hid themselves among civilian houses”.

It added: “The ISAF aircrafts pursued the three remaining insurgents and dropped bombs on a road where they were hiding but as a result, six children were killed and three others were injured.”

ISAF commanders say the Taliban and other armed groups frequently hide among the local population in a bid to protect themselves. However, ISAF forces are supposed to take all possible steps to avoid civilan casualties.

The US general who commands ISAF troops in Afghanistan, General John Allen, wrote in July that he expected “every member of ISAF to be seized with the intent to eliminate civilian casualties caused by ISAF”.

Kandahar police chief General Abdul Raziq said three Taliban had died out of a total death toll of nine, while investigations were continuing to ascertain the identity of the others.

Earlier this month, Afghan elders held a loya jirga or traditional meeting to discuss a strategic partnership deal with the US which will govern Kabul’s relations with Washington after 2014.