Speculation that Meles, 57 - an ally of Washington who twice sent troops into neighbouring Somalia to help crush rebellions - was seriously ill had grown after he failed to attend an African Union summit last month.

Deputy Prime Minister Hailemariam Desalegn will be sworn in as acting prime minister and the ruling party will meet to choose a successor, but no date has been set.

Bereket Simon, Meles' right-hand-man and a government spokesman, said Meles had been ill for a year and had diedafter being rushed to a nearby hospital's intensive care unit.

Meles seized power in 1991 from Mengistu Haile Mariam's military junta and went on to become a towering political figure on the continent.

He was widely credited with steering one of the world's poorest countries to fast economic growth.

Rights groups criticised him for cracking down hard on dissent but the West generally turned a blind eye to the repression, reluctant to pick a fight with a partner in the fight against al-Qaeda-linked groups in Africa.

His secretive government did not reveal where he was being treated or the nature of his illness but an EU source said he died in Brussels at the Saint-Luc University Hospital.

Somalia's al-Shabab Islamic militants, who encountered Ethiopian troops twice during Meles' tenure, once in 2006-2009 and again from December, hailed Mele's death.

Bereket said Africa's second-most populous nation was stable and would continue on the path charted by Meles.