ADDIS ABABA  - Tens of thousands of Ethiopians and many African leaders mourned late strongman Meles Zenawi on Sunday at the first state funeral for a leader of the Horn of Africa nation in over 80 years.

Followed by giant crowds, Meles's flag-draped coffin was carried on a carriage through the capital from the National Palace to the vast Meskel Square, his family dressed in black following behind, many in tears.

The long-serving prime minister, who died last month aged 57, was hailed as an African hero and was a key Western ally in a region home to Al-Qaeda-linked groups, but also criticised by rights groups for a crackdown on basic freedoms.

"The late prime minister was working not only for the renaissance of Ethiopia, but also for the renaissance for all of Africa," deputy Prime Minister Hailemariam Desalegn said in a speech after prayers at Meskel square. Hailemariam, who will lead the government until national elections in 2015, sat behind the coffin, which was placed on a stage above the huge crowd in the square. "All his initiatives will keep going forward, all the transformation plans will progress," he said.

Thousands of soldiers stood guard as the ceremony progressed, some of them crying, before the funeral cortege moved to the capital's Holy Trinity Cathedral, where Meles will be buried. Presidents of all Ethiopia's neighbours - with the exception of arch-foe Eritrea - attended, including Djibouti's Ismail Omar Guelleh, Kenya's Mwai Kibaki, South Sudan's Salva Kiir, Sudan's Omar al-Bashir, and Somalia's Sheikh Sharif Sheikh Ahmed.

South African President Jacob Zuma said Africa had "lost one of the greatest sons of the continent", while Paul Kagame of Rwanda said Meles had "led a humble and simple life, but very meaningful one". Benin's president and current Africa Union chairman Thomas Boni Yayi hailed Meles's "driving force" in efforts to end conflict, while US ambassador to the United Nations Susan Rice praised Meles for his "selfless" efforts.

"Even as we argued whether about economics, democracy, human rights, regional security or our respective foreign policies, I was always struck by two things, Meles was consistently reasoned in his judgments and thoughtful in his decisions," Rice said.

Senior officials from China and the European Union were also attending the funeral.

Religious leaders from Ethiopia's Christian Orthodox Church, dressed in flowing embroidered robes and carrying red and gold velvet umbrellas, held prayers for the sea of mourners.

Meles died in a Brussels hospital on August 20 after a protracted illness. He had not been seen in public for two months, spurring rumours about his health.

The former rebel turned regional strongman took power in 1991 after toppling dictator Mengistu Hailemariam, remaining at the helm of Ethiopia - a relatively stable country in the volatile Horn of Africa region - until his death.

His successor Hailemariam will be sworn in after Meles is buried, although no date has been fixed. He is a relatively unknown politician who hails from the south, unlike many of the country's political elite who are from the north.

While Ethiopia has hosted a series of state funerals in recent decades - including that of popular musician Tilahun Gessesse in 2009 - the last leader to be so honoured was Empress Zawditu in 1930.

Ethiopia's last emperor Haile Selassie, who was murdered in 1975 by coup leaders, is also buried at Holy Trinity Cathedral.