Earlier in the day, Kuwaiti Emir Sabah Al-Ahmad Al-Jaber Al-Sabah, 91, passed away while receiving treatment in the US.

Kuwait's Crown Prince Sheikh Nawaf al-Ahmad al-Sabah has been named Kuwaiti emir by the country's cabinet, succeeding his deceased brother Sheikh Sabah al-Ahmad al-Sabah.

According to the Kuwaiti constitution, the crown prince automatically becomes emir and assumes power after taking oath in parliament.

The cabinet has also announced a 40-day period of mourning for the late Sabah al-Ahmad al-Sabah.

Sheikh Nawaf, 83, had served as the crown prince since 2006, breaking with the tradition of the Al-Sabah family. According to the custom, the offices of emir and crown prince alternate between the Al-Jaber and Al-Salem branches.

He assumed the office of Kuwait's defence minister in 1988 and served until the invasion of the country by the forces of then-Iraqi leader Saddam Hussein as he and the other royals were forced to flee to Saudi Arabia.

After the liberation of Kuwait, Sheikh Nawaf briefly served as the acting minister of labour and social affairs and was then appointed as deputy chief of the Kuwait National Guard, holding that post until 2003.

Following an Amiri decree issued that same year, he became the first deputy prime minister of Kuwait and minister of the interior.

After reports of the emir's death emerged online earlier in the day, the official spokesman for the Kuwaiti government called on the international community to "take information from official sources and not pay attention to what is being raised on social media”.

Kuwaiti Emir Sabah Al-Ahmad Al-Jaber Al-Sabah, 91, has passed away while receiving treatment in the US. Prior to the announcement, Kuwaiti television interrupted regular programming to cut to Koranic verses - a move which often signifies the death of a senior member of the country's ruling family.

الديوان الأميري: ببالغ الحزن والأسى ننعى إلى الشعب الكويتي والأمتين العربية والإسلامية وشعوب العالم الصديقة وفاة المغفور له بإذن الله تعالى صاحب السمو الشيخ صباح الأحمد الجابر الصباح أمير دولة الكويت الذي انتقل إلى جوار ربه pic.twitter.com/NxeybFCx37

— كـــــــــــونا KUNA (@kuna_ar) September 29, 2020

​The announcement comes hours after media reports suggested that Kuwait's ruler had died. However, commenting on these reports, Minister of Amiri Diwan Affairs Sheikh Ali Jarrah Al-Sabah stated that the emir's health is stable and he is receiving a prescribed treatment.

The emir's office said in July that the head of state was hospitalised for medical examinations. The emir's younger brother and the crown prince of Kuwait, Nawaf Al-Ahmad Al-Jaber Al-Sabah, was assigned to temporarily take over a number of emir's constitutional jurisdictions. 

Later in July, Sabah was transferred from Kuwait to the Mayo Clinic in the US city of Rochester, Minnesota, where reportedly underwent surgery to remove two tumours. Since then, the Kuwaiti authorities had repeatedly said that the emir's health condition was stable and he was on the mend.

Last year, Kuwait acknowledged that the emir had suffered an unspecified medical "setback" that required him to be hospitalised.

Sheikh Sabah governed Kuwait, an OPEC oil producer, since 2006 and steered its foreign policy for more than 50 years. He pushed for diplomacy to solve regional issues, such as the ongoing boycott of Qatar by four Arab nations, and hosted major donor conferences for war-torn nations like Iraq and Syria.

Jordan Declares 40-Day Mourning for Deceased Kuwaiti Emir

The Jordanian authorities have declared a 40-day morning following the death of Kuwaiti Emir Sabah Al-Ahmad Al-Jaber Al-Sabah, the office of King Abdullah II said on Tuesday.

"The Royal Hashemite Court mourns the passing of Kuwait Emir Sheikh Sabah Al Ahmad Al Jaber Al Sabah, may his soul rest in peace. By His Majesty King Abdullah’s orders, the Royal Hashemite Court has announced 40 days of mourning over Sheikh Sabah’s passing, as of Tuesday. The Royal Hashemite Court expresses the deepest sympathies of King Abdullah and the people of Jordan, as they stand with the people of Kuwait in these difficult times," the Jordanian king's office said in a statement.

The Kuwaiti emir died earlier in the day while undergoing medical treatment in the United States, as announced by Ali Al-Jarrah Al Sabah, the minister responsible for the emir's affairs.

The emir was hospitalised in Kuwait on July 18 for surgery, reportedly to remove two tumours, and later transported to the US for further treatment. According to the Kuwaiti authorities' communications since his condition was stable and gradually improving.

Emir Sabah IV had ruled Kuwait since 2006. He briefly served as prime minister and foreign minister for several decades before that.