Mohammed Azim, the district prosecutor in Gereshk, Helmand province, was shot by two men on a motorbike who then escaped the scene, said local government spokesman Daud Ahmadi, blaming the killing on the Taliban.
"This morning, on his way to the office, two unknown men shot him," Daoud Ahmadi said. Azim died on his way to hospital, he added.
In the neighbouring province of Kandahar, a civil servant in the provincial wing of the agriculture ministry was shot dead in a similar attack, said Ahmad Shah Roshan, director of the Kandahar agriculture department.
"This is the work of enemies of Afghanistan," he told AFP in reference to the Taliban insurgents who have been fighting to bring down the Western-backed Afghan government since the 2001 US-led invasion ousted them from power.
Just five days ago, a young woman working on rural development for the government was shot dead in Kandahar city.
There was no immediate claim of responsibility for Sunday's assassinations, but the Taliban have stepped up killings of civil servants and Afghans accused of collaborating with US-led NATO troops.
Kandahar is the birthplace of the Taliban and the south has seen some of the worst fighting in the almost 10-year-long war.
In recent weeks, both Kandahar's mayor and the president's powerful brother, Ahmed Wali Karzai, have been assassinated there.
Many judges refuse to work in parts of Afghanistan effectively under Taliban control, where the militia metes out its own justice at Islamic-style courts.
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