New York, Sep 13 (IANS): The Pentagon on Monday said that a US airstrike has killed Islamic State (IS) second-in-command Abu Muhammad al-Adnani, despite Russia's insistence that it was one of its planes that killed him.

IS itself has already said al-Adnani, who also served as the terrorist group's main spokesman, died in the August 30 strike in al-Bab in Syria's devastated Aleppo province, NBC News reported.

Pentagon press secretary Peter Cook said that "the US precision airstrike" specifically targeted al-Adnani and removed IS "chief propagandist, recruiter and architect of external terrorist operations".

Cook said that US "will continue to target IS leaders, relentlessly pursue its external plotters, and, working with partners on the ground".

"We will not rest in our efforts to destroy IS's parent tumor in Iraq and Syria, combat its metastases around the world and protect our homeland," he added.

The Russia Defense Ministry, however, has mentained that al-Adnani was among as many as 40 Syrian rebels who were killed by a Russian Su-34 bomber in Aleppo.