Flags of the proscribed ULFA-I were found in different parts of Assam, including in Guwahati and in three school compounds during the outfit's 'Pratibad Divas' (Protest Day) on Wednesday, police said.
The outfit has been observing November 28 as Protest Day ever since ULFA was declared a banned outfit 21 years ago on this date.
The flags were spotted by locals and CRPF pesonnel and informed the police who immediately removed them.
Two flags of the outlawed United Liberation Front of Asom-Independent were found in Guwahati - one of them in the compound of Borbari High School and another on a nearby hillock, the police said.
The third flag of the militant outfit was found hoisted in Lakhimpur district in the compound of Dakhin Dhalpur Balika Higher Secondary School at Kochua by CRPF personnel, who informed the police about it.
The fourth flag was found hoisted at Chamrajaan in Dhemaji district along NH 15, the sources said adding a fifth one was recovered from the compound of Nagadhuli Janajati HS School at Mariani in Jorhat district.
Deputy Commissioner of Police (DCP), East Guwahati, Ramandeep Kaur said, "It seems to be a handiwork of miscreants. We are investigating the matter. We are interrogating a few people in this connection."