Pakistan gunmen wound polio guard in Karachi
A policeman escorting polio vaccinators has been injured after gunmen shot him in the Pakistani city of Karachi.
The attack took place in the lawless Orangi area. Vaccination efforts have been suspended in the city.
Media reports said the attackers, who were on a motorcycle, fled when police returned fire.
Pakistan is one of only three countries where polio remains endemic. Militants say polio teams are spies or that the vaccine causes infertility.
More than 60 polio workers or police guarding them have been killed in the country in the past two years.
Last year, more than 300 polio cases were confirmed in Pakistan, the highest figure in 16 years.
Monday's attack came as a three-day campaign targeting more than a million children got under way in Karachi.
The police officer is in a critical condition in hospital. Earlier reports said he had been killed.
The BBC's M Ilyas Khan in Islamabad says polio eradication efforts have faced growing opposition from Islamist militants since 2005.
Last year the United Nations recommended all travellers from Pakistan must be given polio drops at airports, causing embarrassment to the country.
Authorities hope for better results this year, our correspondent says.
They say most of the new cases in 2014 originated in, or were linked to, a large population in the Waziristan region where the Taliban had banned vaccinations.
This population has now become accessible following military action since last June that has expelled the militants from many parts of the area.
- Poliomyelitis mainly affects children under five
- Invades the nervous system and can cause total paralysis within hours
- One in 200 infections leads to irreversible paralysis
- Polio cases have decreased by more than 99% since 1988
- Endemic in three countries - Afghanistan, Nigeria and Pakistan
- There is no cure but the virus can be prevented by immunisation
Source: World Health Organization