QUETTA: A policeman was killed Wednesday when assailants opened fire at a polio team on Quetta's Sirki road, police sources said.

They said one passerby child was also injured in the firing. The policeman identified as Zainullah was guarding polio volunteers when he came under the attack.

The assailants managed to escape unhurt from the spot.

Police and personnel of other law enforcement agencies reached the spot and cordoned off the area as investigation into the incident went under way.

There was no immediate claim of responsibility for the attack.

The provincial government of Balochistan launched an anti-polio campaign in Quetta and other sensitive districts of the province to provide polio drops to children below the age of five years.

Quetta’s Health Department had formed 616 teams to ensure administering drops to children in high-risk areas of the city. In view of growing security threats, the government of Balochistan has already deployed policemen to ensure security of the polio teams.

Armed men had attacked a polio team in Eastern Bypass area of Quetta on November 26 last year. Four polio workers, including three female volunteers, were killed in the attack.

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The banned militant group Jundullah had claimed responsibility for the attack

Pakistan is one of only three countries in the world where polio remains endemic, along with Afghanistan and Nigeria. Efforts to eradicate it have been seriously hampered by the deadly targeting of vaccination teams in recent years.

Militant groups often attack polio teams as they see vaccination campaigns as a cover for espionage. There are also long running rumours about polio drops causing infertility.

Balochistan had been polio free for almost more than two years. However, the first polio case was reported from Balochistan's Killa Abdullah district last year in July 2014.

Refusal on the part of parents remained the underlying factor behind increasing cases of polio in Balochistan.