The incident, which took place earlier on May 20, caused an uproar on the aircraft with a passenger filing an official complaint with Pakistan's Civil Aviation Authority.
The couple seated in the fourth row first began kissing, according to eyewitnesses.
The air hostess then requested the couple to desist after the fellow passengers complained. The air hostess later reportedly provided the couple with a blanket to keep their display of affection under wraps as they did not pay heed to her request.
"Who are you to tell us anything?" the couple hit back when confronted over their actions, claimed the passengers.
Couple caught 'kissing' on a Karachi-Islamabad flight. A distressed eyewitness claims airhostess brought blanket for the couple to let them continue 'indecent' activities under the covers.
— Naila Inayat (@nailainayat) May 25, 2021
This is KissingBlanketGate.pic.twitter.com/0VBnKJwFOB
Advocate Bilal Farooq Alvi, who was on board the flight, lodged a complaint with the Civil Aviation Authority against the airline staff for not taking action to stop the couple, The Express Tribune reported.
He also issued a video message on social media claiming to point out the actions of the couple in the presence of families aboard the flight.
The matter is being probed by the authorities.