The U.N. refugee agency's head office in Pakistan has received a letter containing death threats toward one of its international staff members.
A senior police official told VOA on Thursday that a high-level probe of the incident had begun, and that efforts were underway to find the man who arrived in a white car at the UNHCR office in Islamabad to deliver the letter to a security guard there.
The U.N. High Commissioner for Refugees' office is located in Islamabad's highly secured Diplomatic Enclave, which houses mostly foreign embassies, including that of the United States. Visitors are strictly required to seek prior appointments from the concerned offices and are asked to get their car license plates registered with police at the main entrance a day before their arrival.
The UNHCR's complaint registered with police, a copy of which was seen by VOA, says UNHCR security cameras captured images of the man while he was delivering the letter and of his car in the parking area.
"However, due to poor quality of the photograph and video, it was not possible to ascertain the registration number of the car and to identify the driver," according to police.
Police said they suspected that "an insider" could have sent the letter, and they ruled out involvement of Islamist groups. They insisted it was not possible for an outsider to drive into the Diplomatic Enclave without being detected, because security cameras cover the entire area and a heavy police force is permanently deployed there.
The news came as a series of brazen bomb attacks claimed by Islamist militants have killed scores of people in Pakistan over the past fortnight.
The anti-state Pakistani Taliban and local affiliates of Islamic State have claimed responsibility for the deadly violence.
On Wednesday, the military launched a nationwide operation to eradicate the threat of terrorism, responding to the recent wave of militant violence.