Abdul Jabar Qahraman, who was preparing to contest Saturday’s parliamentary polls, was killed in the blast, a senior government official said.
Omar Zwak, a spokesman for the Helmand governor, said another seven people were wounded.
“A bomb was placed below Qahraman’s chair in his campaign office. We are investigating the incident,” Zwak said.
Qahraman is the 10th candidate to be killed in the past two months. Another two have been abducted and four others were wounded by hardline Islamist militants.
Another 22 people were killed at an election rally in northeast Takhar province last week.
The Afghan Taliban claimed responsibility for the attack that killed Qahraman.
The Islamist group has directed Afghans to boycott the much-delayed parliamentary polls and has vowed to continue its fight against the Western-backed Afghan government.
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