The video, which has gone viral on social networking applications like WhatsApp, shows the PDP leader purportedly firing several rounds in air from an AK-47 rifle at his residence.
However, Mir denied having fired any rounds and accused his political rivals of producing a doctored video.
"I did not fire any rounds ... there was a commotion following my victory and the rifle of one of my PSOs (personal security officer) fell on ground which I retrieved and handed it back to him," Mir told PTI.
Former Jammu and Kashmir chief minister Omar Abdullah on Friday urged the police to take action against Mir for brandishing the weapon.
Mir allegedly fired the gun into the air after wresting the Sonawar seat from Omar in the recently held assembly elections in the state.
The National Conference leader took to twitter to express his anguish.
"So, will J&K police register a case against the gun toting MLA or, will they be too scared in case he's a minister a few days from now?" he wrote.
"The PDP chap let off an AK-47 to celebrate his victory over me. Thank goodness I didn't lose Beerwah!!! I wonder what they would have fired!" he added.
A video footage, which was taken on the day of counting of poll results, shows Mir holding an AK-47 and firing gun shots after defeating Omar.
The video has surfaced in the midst of efforts by the PDP to form the state government after the Jammu and Kashmir elections results threw a fractured mandate for the 87-member state assembly.
The PDP emerged as the single largest party, securing 28 seats in the five-phased assembly elections, while the Bharatiya Janata Party bagged 25.
Image: Mohammad Ashraf Mir defeated outgoing Jammu and Kashmir CM Omar Abdullah
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