Islamabad, May 21 (IANS): An anti-polio drive was suspended on Thursday in Pakistan's Quetta city due to authorities' failure to provide adequate security to polio administration teams, media reports said.

A source in the the Balochistan health department said the anti-polio drive would be re-launched on Friday after appropriate security was provided by the administration, Dawn reported.

"There are polio samples in the environment of Quetta ... We fear (there may be) polio cases in Quetta," a source said.

Polio teams have been attacked in Quetta and other parts of Balochistan in the past.

In November 2014, gunmen attacked an anti-polio team in Quetta's Eastern Bypass area and killed four polio workers, including three women volunteers.

The Balochistan health department -- with the support of Unicef and other organisations -- aims to administer polio drops to more than 400,000 children below the age of five years in Quetta during the ongoing campaign.

The campaign, during its first phase, was launched in 18 union councils on Wednesday morning.

"The second phase will be launched on May 25 in different parts of Quetta," said campaign Emergency Centre Coordinator Saifur Rehman in a statement.

During 2015, three polio cases have been reported from Balochistan's Killa Abdullah, Loralai and Quetta areas.

Currently, a polio campaign is underway in Zhob, Sherani, Lasbella and four other districts of the province.

The provincial government has decided to provide anti-polio drops to 1.2 million children in these districts.