A chilling selfie of a man wearing an Isis scarf and standing outside New York's Metropolitan Museum of Art (Met) has emerged online, triggering security scare in the city.

"We are in your home", read the caption of the image that was spotted on messaging app Telegram, which is widely used by the Islamist jihadist group. The selfie is believed to have been posted on the messaging app on 30 December.

Terror watchdog group Memri reported that the image shows the man standing on a snow-covered road outside the museum building near a New York City Police Department (NYPD) security camera, while people can be seen walking by.

Memri added that another picture was being circulated on the messaging app in which a person is seen holding a smart phone with the terror group's logo flashing on its screen, while the rebuilt World Trade Center is in the background.

The NYPD said that it was aware of the images and has launched a probe, New York Post reported, adding that the department did not reveal what action it is taking to verify the credibility of the images. The department, meanwhile, assured that "at this time there are no credible threats related to New York City".

The images surfaced days after Isis issued threats of more attacks in the US, targeting the festive season. In one of the disturbing posters released by the terror group and obtained by Site Intelligence group, a man was seen brandishing a bloodied knife. The poster carried the message: "It's cheaper than a chainsaw."

Law enforcement sources in the US have reportedly said that these kind of pictures keep emerging online but, most of them end up being fakes.

Meanwhile, the images surfaced weeks after an Isis sympathiser, Akayed Ullah, allegedly detonated a pipe bomb strapped to his chest at the Port Authority Bus Terminal in Manhattan during rush hour on 11 December. Several people were injured in the explosion, but no fatalities were reported.

Following his arrest, the 27-year-old Bangladeshi man told investigators that he was inspired by previous terror attacks carried out around Christmas in Europe. He allegedly selected Port Authority as his target after seeing several festive posters on the subway walls.

Local media reports stated that Ullah acted in the name of Isis to avenge the deaths of Muslims killed in the Middle East. He reportedly said he was motivated to launch an attack following US airstrikes against Isis targets in Syria and elsewhere.

Ullah was charged with criminal possession of a weapon, supporting an act of terrorism and making a "terroristic threat".

Selfie of a man wearing Isis face scarf emerges online - Representational image Ali Hashisho/Reuters