The attacker detonated himself in a market place in Ghazni province, two days after another bomber struck outside government buildings in the north of Afghanistan killing 14 people including a provincial politician.
“At around 5:00 pm, a 18-year-old suicide attacker blew himself up in a market in the district of Muqur,” Ghazni province deputy governor Mohammad Ali Ahmadi told AFP.
“As a result, four anti-Taliban fighters and three civilians were killed and 14 others injured.”
Local army spokesman Nazifullah confirmed the incident and death toll to AFP.
There are many small bands of tribal militia across Afghanistan who fight against the Taliban insurgents who were toppled from power in 2001. The groups deny receiving weapons and support from the government.
The Taliban launched their annual “spring offensive” last month vowing to use suicide blasts to inflict maximum casualties and warning Afghans working for President Hamid Karzai’s regime to distance themselves from the government.
All NATO combat missions will finish in Afghanistan by the end of 2014 and foreign troops have already begun to withdraw from the battlefield as Afghan police and army take over the fight against the insurgents.
More than 11 years after the Taliban regime was ousted, efforts to seek a political settlement ending the violence have so far made little progress, but pressure is growing ahead of the NATO withdrawal.
Also on Wednesday, officials said that unknown gunmen dragged the father of Afghanistan’s cricket captain from his car on the outskirts of Jalalabad city and have taken him hostage.
Mohammad Nabi, who took over the captaincy of the team in March, confirmed that his father, Khobai Isakhel, had been kidnapped in the eastern province of Nangarhar on Tuesday.
“I have no idea who the kidnappers might be, they have not contacted me,” Nabi told AFP, declining to give any more details.
Ahmad Zia Abdulzai, spokesman for the Nangarhar provincial government, said: “Yesterday at around 10:00 am, unknown armed man seized him from his car. No trace of him has yet been found.”
Kidnapping is rife in Afghanistan’s major cities, with criminal gangs demanding large ransoms for the release of hostages.