International aid group Save the Children has had its office in Islamabad sealed by police, with orders from the Interior Ministry that all expatriate staff leave the country.

No formal announcement was made by the government but an official from the interior ministry told Agence France Presse that the NGO was involved in "anti-Pakistan activities."

"Their activities were being monitored since a long time. They were doing something which was against Pakistan's interest," the official said.

Government officials, accompanied by police, placed a lock on the compound gate after working hours.

"We have sealed the office of Save the Children on government instructions. We don't know the reasons behind the order. We were sent a three-line notification by the interior ministry saying that this office should be sealed and all the expatriate staff be sent back to their countries within 15 days," Kamran Cheema, a senior government official said.

Local police chief Hakim Khan told AFP that a police officer was standing guard outside the charity's compound and that he was "unaware of the reasons behind closing down the Save the Children's office."

No prior warning from the government

A spokesperson for Save the Children said that its Islamabad office had been sealed without warning.

"We strongly object to this action and are raising our serious concerns at the highest levels," the spokesperson said, adding that the NGO did not have any expatriate staff working in Pakistan.

"All our work is designed and delivered in close collaboration with the government ministries across the country, and aims to strengthen public service delivery systems in health, nutrition, education and child welfare."

In 2012, Pakistan claimed that the aid group was linked to Pakistani doctor Shakeel Afridi who the US Central Intelligence Agency (CIA) allegedly used to carry out a fake vaccination programme as part of their campaign to flush out al-Qaeda leader Osama bin Laden.

Although the charity denied any links with either the doctor or the CIA, its expat staff were forced to leave Pakistan.