Abdel-Aziz al-Hilu, leader of the rebel faction Sudan People’s Liberation Movement-North (SPLM-N), has called on Sudanese to come on to the streets to demand that the president step down.

Angry citizens have taken to the streets in several cities since last week, leading to a crackdown in which dozens of protesters have been killed.

In an audio message released on Thursday, the Sudanese rebel leader says the country’s political and economic conditions have become unbearable, calling on the people of Sudan to topple the current government to preserve Sudan’s unity.

The message comes as anti-government demonstrations over rising food prices intensify.

“We call upon all Sudanese irrespective of their political affiliations to take part in the popular uprising,” al-Hilu said.

He accused the government of deliberately starving downtrodden groups. Al-Hilu urged an escalation of anti-government protests across the country to challenge the 29-year rule of president Omar al-Bashir.

Al-Hilu, who has been fighting the government since 2011, called for a modern, democratic and secular state in Sudan where equal rights to all citizens are guaranteed.

“I call upon the supporters of SPLM-N to take to the streets and to participate effectively in the popular uprising and the battle of dignity and freedom,” he said.

The armed opposition leader condemned the excessive use of lethal force by security forces against protesters.

While the government puts the death toll from the protests at 19, the London-based rights group Amnesty International says at least 37 people have been killed in the protests.

The demonstrations began initially over rising prices and shortages of food, but later escalated into calls for President Omar al-Bashir to step down.