Ethiopian Prime Minister Meles Zenawi has died at the age of 57, state media say, after weeks of illness.

Mr Meles died in a hospital abroad, said state media and a government spokesman, but they did not say exactly where or give details of his ailment.

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

Mr Meles took power as the leader of rebels that ousted communist leader Mengistu Haile Mariam in 1991.

"Prime Minister Meles Zenawi passed away yesterday [Monday] evening at around midnight," government spokesman Bereket Simon said, adding that he was "abroad" when he died, according to AFP news agency.

"He had been recuperating well, but suddenly something happened and he had to be rushed to the ICU [intensive care unit] and they couldn't keep him alive."

State television said he had died after contracting a "sudden" infection.

Deputy Prime Minister Hailemariam Desalegn, who is also Ethiopia's foreign minister, will be acting head of government, state television said.

"Even if Ethiopia has been badly affected for missing its great leader, Prime Minister Meles Zenawi initiated fundamental policies and strategies which will be further strengthened," the TV said.

Mr Meles had not been seen in public for some eight weeks prior to his death, and was reported to have been admitted to hospital in July.

But three weeks ago, the spokesman Mr Bereket told the BBC that he was in "a good condition and recuperating", and dismissed reports he was critically ill.

At the time he declined to give any details about Mr Meles' whereabouts or what he was suffering from.

But reports suggested Mr Meles was in hospital in Belgium, suffering from a stomach complaint.

Meles Zenawi, who died in hospital at the age of 57, was the cleverest politician to emerge from the Tigray People's Liberation Front (TPLF), one of the armed movements which spear-headed the struggle against Ethiopia's military regime in the 1970s and 1980s.

Born into a middle-class family in Adawa, Tigray, in Ethiopia's northern highlands, he dropped out of university to join the insurrection.

After the military council (Derg) led by Mengistu Haile Mariam was finally overthrown in 1991, Mr Meles first became president in a transitional government and then, in 1995, prime minister. He went on to dominate Ethiopian public life until his death.