President Donald Trump said on Tuesday the U.S. military had killed the person who likely would have succeeded Abu Bakr al-Baghdadi as the leader of Islamic State.

Trump did not identify the person or give more detail on how he was killed in his tweet on Tuesday.

An administration official later said the President was referring to Abu al-Hassan al-Muhajir - the Islamic State spokesman and a high-ranking figure within the jihadi group.

'Just confirmed that Abu Bakr al-Baghdadi's number one replacement has been terminated by American troops,' Trump said on Twitter.

'Most likely would have taken the top spot - Now he is also Dead!'

President Donald Trump said on Tuesday the U.S. military had killed the person who likely would have succeeded Abu Bakr al-Baghdadi as the leader of Islamic State

Trump did not specify who he was referring to, but the United States on Monday confirmed the killing of Abu al-Hassan al-Muhajir, Islamic State spokesman and a high-ranking figure within the jihadi group

The U.S. had already confirmed on Monday the killing of al-Muhajir.

Muhajir was killed in a separate operation in northern Syria in a joint raid between Kurdish-led and U.S. forces.

Syrian Democratic Forces General Commander Mazloum Abdi said it was 'a continuation of the previous operation' in which Baghdadi was killed over the weekend.

Mazloum described the jihadist spokesman as Baghdadi's right-hand man.

Muhajir was killed in the Syrian town of Jarablus in Aleppo province, according to a senior State Department official.

The official said the operation led to 'the demise of (Baghdadi's) No. 2, or one of his No. 2s'.

The U.S. on Monday confirmed the killing of Abu al-Hassan al-Muhajir (left) - the Islamic State spokesman and a high-ranking figure within the jihadi group. It came after Trump on Sunday announced the killing of Baghdadi (right) by U.S. special operations forces in northwestern Syria

Abu Hassan al-Muhajir, the Islamic State group's spokesman, was killed in a raid on Sunday in the northern Syrian village of Ayn al-Bayda near Jarablus (pictured above)

It came after Trump on Sunday announced in a national address from the White House the killing of Baghdadi by U.S. special operations forces in northwestern Syria.

In the aftermath of Baghdadi's death, ISIS was believed to have a new leader - Abdullah Qardash, also known as Hajji Abdullah al-Afari.

Qardash, nicknamed The Professor or The Destroyer because of his reputation as a brutal legislator, was said to have been nominated by Baghdadi to take over if he died.

According to a statement by Amaq, ISIS's press agency, Baghdadi appointed Qardash to run the group's day-to-day operations in August this year - making him the heir-apparent after his former boss killed himself during a raid by U.S. forces in Syria on Saturday.