UN Secretary-general Ban Ki- moon and two UN agencies on Tuesday condemned the "senseless and inexcusable" killing of at least six people working on a polio vaccination campaign in Pakistan in the past 24 hours, a UN spokesman said here.

"The secretary-general joins the World Health Organization (WHO) and UNICEF (the UN Children's Fund) in condemning these senseless and inexcusable attacks on health workers," Martin Nesirky said at a daily news briefing.

The secretary-general would meet on Tuesday with the Pakistani permanent representative to the UN, Masood Khan, who will take over the rotating presidency of the Security Council next month. During that meeting, Ban is expected to express his condolences and condemn those attacks, Nesirky said.

The six victims, reportedly five Pakistani women and one man, were shot dead in the city of Karachi in Sindh Province and in the city of Peshawar in Khyber Pakhtunkhwa Province, respectively. Pakistan is one of three countries, along with Afghanistan and Nigeria, where polio is still endemic.

The WHO and UNICEF said in a joint statement that those killed were among thousands who work selflessly across Pakistan to help eradicate polio, the spokesman said. "They said that such attacks deprive Pakistan's most vulnerable populations -- especially children -- of basic life-saving health interventions," he added.

"We call on the leaders of the affected communities and everyone concerned to do their utmost to protect health workers and create a secure environment so that we can meet the health needs of the children of Pakistan," the two agencies were quoted as saying in the statement.

According to the joint statement, the government of Pakistan and the affected provinces have temporarily suspended the vaccination campaign due to concerns over the safety of health workers.

Polio is a highly infectious disease caused by a virus that can cause permanent paralysis in a matter of hours. Safe and effective vaccines protect children from the disease.