Burundi's President Pierre Nkurunziza has died at the age of 55 after suffering a heart attack. 

The Burundian Government confirmed the sudden death of President Pierre Nkurunziza in a statement published on its official twitter page.

"The Government of the Republic of Burundi announces with great sadness the unexpected death of His Excellency Pierre Nkurunziza, President of the Republic of Burundi... following heart failure on June 8, 2020," the post said.

URGENT: Le Gouvernement de la République du Burundi annonce avec une très grande tristesse le décès inopiné de Son Excellence Pierre Nkurunziza, Président de la République du Burundi, survenu à l’Hôpital du Cinquantenaire de Karusi suite à un arrêt cardiaque ce 8 juin 2020. pic.twitter.com/PP46kKzAM5

— Burundi Government (@BurundiGov) June 9, 2020

According to the statement, the outgoing president was admitted at Karusi Hospital in central Burundi on Saturday after feeling unwell. His condition then improved but on Monday he had a cardiac arrest and efforts to revive him were unsuccessful.

Nkurunziza, who has been in power in Burundi since 2005 was due to be replaced in August by political ally Evariste Ndayishimiye, who was declared earlier this month the winner of a May 20 presidential election.