An African Union envoy is in Sudan to mediate the crisis as leaders of the country's protest movement accuse the ruling military of pursuing a brutal crackdown on protesters.

The Sudanese Professionals Association, which was behind rallies that drove longtime autocrat Omar al-Bashir from power in April, released a statement on Thursday saying the military authorities are arresting and intimidating people who took part in a general strike this week.

Activists called off the strike and civil disobedience campaign as the U.S. and Ethiopia stepped up efforts to find a peaceful solution to the crisis, following last week's clampdown by security forces on pro-democracy demonstrators that killed over 100 people.

The AU envoy to Sudan, Ahmed Labbat, was to brief the media later in the day on his mediation efforts.