What is behind Ethiopia's wave of protests?

Ethiopia's Olympic marathon silver medallist Feyisa Lilesa crossed his hands above his head as he finished the race in Rio - bringing the world's attention to a wave of protests in his home country.

It is an anti-government gesture used by protesters in the Oromia region.

Ethiopia's government normally keeps a tight grip on the country and there has not been anything on this scale in the last 25 years.

There has not been a specific trigger and what we are seeing is an accumulation of years of frustration from ethnic groups who say they have been marginalised by the government.

Demonstrations began in Oromia last November. Protests have also sprung up more recently in the Amhara region.

Oromia and Amhara are the homelands of the country's two biggest ethnic groups.

New York-based Human Rights Watch says that more than 400 people have been killed in clashes with the security forces in Oromia, although the government disputes this figure.

The Oromos, who make up around a third of the population, have long complained that they have been excluded from the country's political process and the economic development which has seen the capital, Addis Ababa, transformed in recent years.

The protests were initially over a plan to expand the boundaries of Addis Ababa into the Oromia region.

That plan was dropped, but the demonstrations exposed some underlying issues and protests continued with the latest round taking place on Saturday in many places in Oromia and the capital, Addis Ababa.

At the root of the recent demonstrations in Amhara is a request by representatives from the Welkait Amhara Identity Committee that their land, which is currently administered by the Tigray regional state, be moved into the neighbouring Amhara region.

The Welkait committee says community members identify themselves as ethnic Amharas and say they no longer want to be ruled by Tigrayans.

Amharas used to form the country's elite and the language, Amharic, remains the most widely spoken in the country.

Source: CIA World Factbook estimates from 2007

Observers say that Ethiopia's governing coalition is dominated by the party from the small Tigray region (TPLF), that led the guerrilla war against the military regime of Colonel Mengistu Haile Mariam. Some see both sets of protests as a way of criticising the country's government.

There is no formal connection between the Amhara and Oromia demonstrations but at a recent protest in Gondar, banners could be seen expressing solidarity with people from the Oromia region.

Oromo activists referred to the demonstrations in Amhara in their Facebook post calling for protests on the first weekend in August - when Amnesty International said that more than 100 people died - but highlighted the fact that they thought the protesters there had been treated more leniently.

The central government, a close ally of the West, is in a very powerful position and has total control over the security forces.

There is not a single opposition member in parliament, so it faces no real political threat.

But its reaction to a big protest at the beginning of August suggests that it is worried: It shut down the internet across the country for two days, fearing that was how the demonstrations were being organised.

There is only one, state-controlled internet service provider so this was fairly straightforward.

Prime Minister Hailemariam Desalegn then issued a veiled threat to protesters saying that the government was obliged to ensure the rule of law. But he did not specify what that meant in practice.

He also appeared to be concerned that the country was sliding into ethnic conflict, which could become difficult to contain.