|Afghan security personnel, both in the army and private security firms, have been heavily targeted by Taliban [GETTY]
Nine private security guards have been killed and three wounded in a Taliban attack on a checkpoint set up to protect a construction site in southern Afghanistan.
Elsewhere in the country, three civilians died and five other people, including a policeman, were wounded when a group of improvised explosive devices blew up beneath a bridge in Herat.
The construction site attack occurred early on Monday morning in Nad Ali, a town in Helmand province. The Taliban has claimed responsibility, making it the group's second attack on a construction company in the past 24 hours.
All of the guards killed in the attack were Afghan citizens, Al Jazeera's Sue Turton reported. The construction company was working on a road that links Nad Ali to Highway 1, also called the Ring Road, she said. The Ring Road is Afghanistan's major highway, circling the entire country.
The Taliban has threatened to kill anyone who participates in reconstruction projects connected with or funded by the international community.
On Sunday, Taliban fighters attacked another construction company in Farah province, west of Helmand, capturing 20 workers. Two fighters were killed in the attack, and the workers are still being held.
The issue of private security guards in Afghanistan has been controversial for years. Security contractors have been accused of killing civilians unjustifiably, carrying illegal guns and importing weapons illegally into the country.
But on Sunday, the Afghan government backed away from an August decree by Hamid Karzai, the Afghan president, that called for a total ban on private security guards by 2011.
Karzai's administration will now allow private guards to provide security "for embassies, transport of diplomats, diplomatic residences, international forces' bases and depots can continue operation within these limits", the AFP news agency reported.
Many experts worried that a total ban on private security with a four-month deadline not only would come too fast for indigenous Afghan forces to replace the guards but also place diplomats and foreign and Afghan non-governmental organisation workers in danger, since private guards are considered better trained than the Afghan police and army.
Karzai's decree aimed to take security out of the hands of private contractors viewed by the adminsitration as often too trigger-happy and a competing base of power within the country. It would have put the Afghan army and police in charge of such duties.
In a brief statement Sunday, according to the AFP, Karzai's office said that "concerns expressed by Nato commanders and foreign embassies about the dissolution of private security companies" had been considered.
"Other private security companies pose a serious threat to internal security and national sovereignty, and the dissolution process will continue with no exception," the statement said.