The Islamabad police on Monday registered a first investigation report (FIR) regarding the appearance of a flag supposedly belonging to the self-styled militant Islamic State (IS) group on the outskirts of the capital.

The FIR, which includes clause 7 of the Anti-Terrorism Act, has been registered at the Khanna Police Station.

Law enforcement agencies swung into action on September 24 after the flag, spotted on a bridge near Iqbal Town in Khanna police precincts, triggered a debate on social and electronic media over whether it belonged to the IS or not.

Taking notice of the rumours, Interior Minister Ahsan Iqbal, before leaving for a trip to China, had asked the Islamabad inspector general of police (IGP) to look into the matter and submit a report.

Khanna Police Station House Officer Abdul Sattar had earlier told Dawn that the flag did not belong to IS.

The flag came to the attention of authorities after a had citizen reported it to police. A team from Khanna police had reached the spot and removed the flag.

Investigators were not able to determine who had hoisted the flag and when questioned, the citizen who gave police the initial information said that he saw the flag while passing through the area and assumed that it belonged to the terrorist organisation, as it was similar to IS flags he had seen in television reports.

The flag, which was black in colour, bore the message “The caliphate is coming”, along with names of Allah, the Holy Prophet (peace be upon him) and the first Kalma.

“After receiving information about the flag, we removed it immediately, but despite our best efforts, it could not be confirmed whether the flag belongs to a party or a group. It could be mischief or a prank,” the Khanna SHO had said. “The IGP has called a late night meeting to discuss the issue and a report will be submitted to the minister for interior."

“It can also be an attempt to see whether our law enforcement and intelligence agencies are capable of solving such cases, whether they can trace the culprits or not. We will also check if we can get any help from the Safe City Project,” a police official had said while impressing that the matter should not be ignored.

The last time such flags were spotted near the federal capital was in Nov 2014, when a number of flags were seen on electricity poles near the highly-secured Pakistan Ordnance Factories at Wah.

Three years have passed, but the Punjab Counter Terrorism Department (CTD) has been unable to identify who placed those flags.

A senior Rawalpindi police officer had told Dawn that following the discovery of the suspect flag in Islamabad, police had intensified search operations in the garrison city and were taking all possible measures to avert anything that could disturb the peace.