video published online by Islamic State (IS) militants claims to show Jordanian pilot Moaz al-Kasasbeh being burned alive.
The video, which could not immediately be verified, showed a man standing in a cage and engulfed in flames.
Lt Moaz al-Kasasbeh was captured when his plane came down near Raqqa, Syria, in December on a mission to support the US-led military coalition against IS.
Jordan has been attempting to secure his release as part of a prisoner swap.
he video posted online on Tuesday was distributed via a Twitter account known as a source for IS propaganda.
A relative of Lt Kasasbeh told Reuters news agency that the Jordanian armed forces had informed the family that he had been killed.
Jordan had offered to free Sajida al-Rishawi, on death row in Jordan for her role in hotel bombings in Amman in 2005, in return for the release of Lt Kasasbeh.