Nairobi/Addis Ababa  - Ethiopia's Supreme Court on Monday sentenced exiled former dictator Mengistu Haile Mariam to death in absentia for presiding over a 17-year rule that saw tens of thousands tortured and killed.

The BBC reported that the court overturned a 2007 High Court ruling that sentenced Mengistu and 18 of his senior aides to life imprisonment.

The presiding judge said that the actions of Mengistu and his aides during his reign amounted to genocide.

Mengistu came to power in 1974 after toppling Haile Selassie, Ethiopia's last emperor.

Between 1977 and 1978, his regime - known as the Derg - embarked on a campaign of torture and murder of intellectuals and political opponents that became known as the Red Terror.

Mengistu fled to Zimbabwe in 1991 as rebel forces closed in. He has remained there under the protection of his ally President Robert Mugabe.

Zimbabwe refused to extradite Mengistu following the original life sentence in 2007, and Mugabe is considered unlikely to change this stance.

However, should Mugabe lose to opposition leader Morgan Tsvangirai in next month's presidential run-off elections, this could change.

Tsvangirai's party has previously indicated it would not protect Mengistu should it come to power.

Mengistu was originally found guilty of genocide in 2006 following a 12-year trial in which witnesses said they had to pay for the bullets used to kill their relatives.

The prosecution then appealed the 2007 life sentence verdict. (dpa)