At least 23 people died when a fire broke out at a prison housing high-profile politicians in the Ethiopian capital, state-controlled media have said citing a government statement.

The blaze erupted on Saturday at Addis Ababa's high security Qilinti prison, where many opposition figures and journalists are held in a country gripped by a wave of protests.

Fana Broadcasting Corporate cited a government statement on Monday as saying 21 inmates died from stampede and suffocation. The other two were killed while trying to escape.

Ethiopia protests: Fast facts

- Protests in Oromia started in November last year when the government announced a plan to expand the capital - a city-state - into the surrounding Oromia region.

- Many Oromos saw that as a plan to remove them from fertile land. The scheme has since been dropped, but the unrest spread as demonstrators called for the release of prisoners and for wider freedoms.

- In the Amhara region, demonstrations began over the status of a district - Welkait - that was once part of Amhara but was incorporated into the neighbouring Tigrayan region more than 20 years ago. Those demonstrations have also since widened.

- The ruling Ethiopian People's Revolutionary Democratic Front is a multi-ethnic coalition made up of four parties. The opposition and political analysts, though, say it is dominated by the Tigrayan People's Liberation Front.

An earlier government statement had said only one person died in the fire. 

There has been no word on the cause of the fire.

Local media and opposition activists on Saturday reported gunfire heard from the prison as it burned. Amateur videos posted online showed a thick plume of dark smoke rising from the site on the outskirts of the city.

Two buildings were damaged in the fire while nine prisoners and police were being treated for injuries, Fana reported.

The remaining inmates have reportedly been moved to other facilities. 

Qilinto houses many of those arrested in an ongoing government crackdown against months of protests in the central Oromo region and elsewhere.

According to the New York-based Human Rights Watch group at least 500 people have been killed by security forces since the protests began in November.

Though demonstrations started among the Oromo, Ethiopia's biggest ethnic group, they later spread to the Amhara, the second most populous group.

Both groups say that a ruling coalition is dominated by the Tigray ethnic group, which makes up about 6 percent of the population.

The government has denied that violence from the security forces is systemic, though a spokesman told Al Jazeera that police officers "sometimes take the law into their own hands", pledging an independent investigation.

Authorities have blamed opposition groups inside and outside of the country and what they have called "anti-peace" elements for the chaos.

Source: Agencies