South Sudan's President Salva Kiir said Wednesday that a six-month delay agreed with his rivals for the formation of a unity government was not enough time to resolve outstanding issues.

Sudanese protest leaders on Wednesday threatened to launch a nationwide campaign of civil disobedience after accusing the country's military rulers of delaying the transfer of power to a civilian administration.

Sudanese artist Rashid Drar used to work from home. Now the 44-year-old's canvas is any empty piece of wall he can find by a month-long sit-in outside the Defence Ministry in Khartoum.

Demonstrators remain camped out in the soaring heat of Khartoum calling for civilian rule three weeks after the military ousted veteran leader Omar al-Bashir.

Protest leaders are to hold talks Saturday with Sudan's military rulers who have so far resisted calls to transfer power to a civilian administration, two leading figures in the protests told AFP.

Support within Sudan for embattled President Omar al-Bashir seems be waning as some ranks in the army, a major pillar of his three decades in power, appear to be tilting towards the demonstrators, analysts say.

Sudanese security forces fired tear gas early Tuesday at thousands of anti-government protesters who had been demonstrating outside army headquarters for a third straight night, but soldiers intervened firing in the air, witnesses said.

Sudan's army deployed around its Khartoum headquarters Monday as thousands of protesters urging the military to back calls for leader Omar al-Bashir's resignation defied tear gas to demonstrate for a third day, witnesses said.

Thousands of protesters held a sit-in outside Sudanese President Omar al-Bashir's residence in central Khartoum on Sunday, having camped there overnight following the biggest demonstration in months of protests against his 30-year rule

Sudanese President Omar al-Bashir on Monday acknowledged the "legitimate" demands of anti-government protesters, while blaming several deaths on the actions of political groups.

Hundreds of protesters, mostly students, took to the streets in and near Sudan's capital Khartoum on Monday, continuing a three-month wave of demonstrations that has posed the most serious challenge yet to President Omar al-Bashir's three-decade rule.

Crowds of protesters rallied Sunday in Sudan to show solidarity with the unemployed, witnesses said, amid an economic crisis that has fuelled months of demonstrations against President Omar al-Bashir's rule.