PARMOLO, Pakistan -- Unidentified attackers have shot dead two women working in an anti-polio drive in northwestern Pakistan.

The shooting occurred on January 29 in the village of Parmolo in the Swabi district of Khyber Pakhtunkhwa Province.

The two were participating in a polio-immunization campaign in the area, local police told RFE/RL.

There was no immediate claim of responsibility.

Police and locals said the two polio workers were attacked by armed motorcyclists. Authorities said they had launched an investigation.

In the past decade, Taliban militants have killed scores of health workers and police officers guarding them because they believe polio-vaccination campaigns are intended to sterilize Pakistani children.

Pakistan, one of the three countries in the world where polio is still endemic, regularly carries out anti-polio drives.