Nigeria has the highest number of prisoners on death row at a time most countries in sub-Saharan Africa are making efforts to abolish capital punishment.

According to Amnesty International, some 621 people were sentenced to death in 2017, raising the number to 2,285 of people on death penalty.

The global watchdog decried the rising number of the sentences, noting that in 2016, the courts sentenced 527 people to death row, a sharp increase from 171 people in 2015.

No executions, however, have been carried out.

Amnesty said only 68 death sentences were commuted last year.

"The country bucked the trend seen elsewhere in the region, as sub-Saharan Africa made great strides in the global fight to abolish the death penalty," Amnesty said.

Guinea become the 20th sub-Saharan state to abolish death penalty, Amnesty said.

Burkina Faso and Chad also took steps to repeal the punishment with new or proposed laws.

“The leadership of countries in this region gives fresh hope that the abolition of the ultimate cruel, inhuman and degrading punishment is within reach,” the watchdog said.

“Unfortunately, some states in Nigeria continue to expand the scope of death sentences,” Amnesty noted.

Last year, three Nigerian states – Benue, Bauchi and Lagos – enacted laws providing for the death sentence for kidnapping.

“With governments in the region continuing to take steps to reduce and repeal the death penalty well into 2018, the isolation of the world’s remaining executing countries – such as Nigeria – could not be starker.”

Amnesty reported a drop in the number of executing countries across sub-Saharan Africa, from five in 2016 to two in 2017, with only South Sudan and Somalia known to have carried out executions.