The Taliban militant group on Wednesday claimed responsibility for killing an Afghan parliamentary candidate and three of his advisers days before parliamentary elections.

A bomb had been planted in a sofa at Afghan politician Abdul Jabar Qahraman's campaign headquarters in the Helmand city of Lashkargah. It exploded while he was in a meeting with advisers.

In a statement, the Taliban said they had killed him and described him as "a renowned communist."

Qahraman served as a commander for the Soviet-backed Democratic Republic of Afghanistan during the Soviet-Afghan War in the 1980s. He was also appointed a regional security adviser to Afghan President Ashraf Ghani in 2016, but later stepped down.

'Brutal acts'

In the wake of the attack, President Ghani condemned the group, saying they will not undermine citizens' faith in democracy.

"Such brutal acts of the terrorists and their supporters cannot weaken people's trust in the peaceful and democratic processes," said Ghani.

Read more: Afghanistan election: Can young candidates turn things around?

Qahraman is the second parliamentary candidate assassinated in Helmand province in the run-up to the election. In total, 10 candidates have been killed across the central Asian country this year.

Unending war

The Taliban are against elections in Afghanistan, describing them as a foreign political process imposed by Western nations in the wake of the US-led invasion in 2001. The militant group has waged a 17-year insurgency against the US, its allies and Washington-backed Afghan forces.

Although NATO's mission has since transformed into an advisory and assistance operation, Western forces in the country continue to be targeted by the Taliban and other militant groups operating in the country.

Late Tuesday, unknown militants fired upon a German military helicopter during a flight from Masar-i-Sharif to Kunduz. Soldiers on board returned fire. However, it is unclear whether the militants sustained any casualties. No German soldiers were injured in the incident.

Tens of thousands of people have been killed and many more injured since the US-led invasion of Afghanistan in 2001 in the wake of the September 11 attacks.

Read more: EU states push ahead with Afghanistan deportations, despite increased danger

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ls/msh (AP, AFP, Reuters, dpa)