Sudan's protest leaders are calling for mass rallies across the country amid deadlocked negotiations with the ruling military over its handover of power.

The Sudanese Professionals' Association, which has spearheaded four months of protests that drove Omar al-Bashir from power in April, says it's also calling for a "million man march" outside the military headquarters in Khartoum.

Thursday's statement, posted on Facebook, says the protesters want to denounce the ruling generals' resistance to relinquish power to a sovereign council that both side had already agreed should lead the country during the transitional period.

There are also indications that the SPA, a union umbrella, may call for a general strike.

The two sides have held several rounds of talks since the military overthrew al-Bashir on April 11, ending his 30-year reign.