The so-called Islamic State confirmed that their leader Abu Bakr al-Baghdadi and his spokesman had died in an audio recording posted online on Thursday.
The disclosure comes five days after US President Donald Trump announced that al-Baghdadi killed himself when pursued by US special operations forces. The Pentagon released video of the raid that resulted in al-Baghdadi's death on Wednesday.
Trump said on Tuesday that al-Baghdadi's "number one replacement" had also been killed, and US national media later reported that a State Department official said that the group's spokesperson had died.
Many experts said the named successor, Abu Ibrahim al-Hashemi al-Quraishi, and new spokesman were not familiar names.
Charles Lister, a Senior Fellow, Director of Countering Terrorism & Extremism programme at the Middle East Institute in Washington DC, wrote on Twitter that the group was making the claim that the new leader and spokesman were "descendants of the Prophet Mohammed's Quraysh tribe."
The director of nonstate programmes at Washington DC's Center for Global Policy, Hassan Hassan, said there was no way to narrow down who the leaders might be.
The terrorist group also vowed revenge against the United States.