At least six policemen were killed on Sunday morning when a powerful blast rocked Lashkar Gah city, the provincial capital of Helmand province, 555 km south of capital Kabul, an official told Xinhua.

"I do confirm so far six policemen were killed in a blast near the gate of provincial police department in Lashkar Gah that occurred at around 08:30 a.m. Sunday," Daud Ahmadi, spokesman for provincial government said.

He said police has started the investigation and details will be released to media after that.

Security personnel have cordoned off the area in precautionary measures.