Addis Ababa (Alshahid)-Ethiopian Prime Minister Meles Zenawi has died at the age of 57, after weeks of illness. Ethiopian authorities announced Tuesday.

“Prime Minister Meles Zenawi passed away yesterday evening at around midnight,” government spokesman Bereket Simon said, adding that the 57-year-old “was abroad” when he died, without giving further details.

Speculation about his health mounted when he missed an African Union summit in Addis Ababa last month.

Meles seized power in 1991 from Mengistu Haile Mariam’s military junta. As president and then prime minister he turned Ethiopia into a key player in regional security affairs.

Ethiopian troops invaded Somalia for a second time last year – after a US-backed invasion in 2006 – and are supporting the fight against Alshabab militantss battling the Western-backed government.

Zanawi has been accused of crushing dissent, using national security concerns as an excuse to silence opposition figures and journalists.

According to Ethiopia’s constitution, Deputy Prime Minister Hailemariam Desalegn is to “act on behalf of the prime minister in his absence”.

Government officials are expected to hold a press conference later Tuesday Diplomats and analysts in Addis Ababa say it has not been clear how the government has been run since Meles was reported to have fallen sick in June.

Meles is survived by his wife, Azeb Mesfin, a member of parliament, with whom he had three children.