'Hey scumbag, tell bin Laden I said what's up' - Robert O'Neill to al-Baghdadi

Robert J O'Neill, the man who allegedly killed Osama bin Laden in 2011, has reacted to the killing of Islamic State leader Abu Bakr al-Baghdadi on Twitter.

The former Navy SEAL expressed support for the US forces that carried out the attack - and directed a message at the deceased IS leader.

"Hey scumbag, tell bin Laden I said what's up," O'Neill said, presumably hoping the terrorist leaders meet up in the afterlife.

Al-Baghdadi killed himself and three young children after detonating an explosive suicide belt, while being chased by Delta Force soldiers on October 26 (local time).

The operation was code-named Kayla Mueller, after American humanitarian worker Kayla Mueller who was tortured and repeatedly sexually abused by Baghdadi.

The raid was launched based on intelligence gathered by the US, Iraq, the Kurdish-led Syrian Democratic Forces and Turkey.

O'Neill told the Delta Force soldiers they did a "great job".

"We've once again proven that it doesn't matter where you hide... we will find you. Great job guys."

O'Neill, aged 43, says he fired the fatal shots that killed bin Laden during SEAL Team 6's May 2011 operation in Pakistan that left the al-Qaeda leader dead.

His claims, which have not been confirmed or denied officially, have been criticised by several fellow Navy SEALs.

Two of them - Rear Admiral Brian Losey and Force Master Chief Michael Magaraci - issued a public statement, stating that "a critical tenant of our ethos is 'I do not advertise the nature of my work, nor seek recognition for my actions'."

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