Sudanese President Omar al-Bashir came under mounting pressure Tuesday as three Western nations pushed for a political transition after months of unprecedented protests against his rule.
Thousands of people remained at the army's headquarters on Tuesday night – where they have been encamped since Saturday – bathed in a sea of light as they held up their mobile phones as torches.
Angry protesters chanting "overthrow, overthrow," have taken to the streets of the capital and towns and villages across the country since December, in the biggest challenge yet to Bashir's two-decade rule.
The country's police on Tuesday ordered its personnel to avoid intervening against the demonstrators.
"We call on God to preserve the security and calm of our country ... and to unite the Sudanese people... for an agreement which would support the peaceful transition of power," a police spokesman said in a statement.
The protesters sang revolutionary songs and anti-government slogans at the facility, which also houses Bashir's residence.
"Since April 6, I'm camping here every night," said businessman Ali Gamereddine.
April 6 is the anniversary of a popular uprising that ousted the regime of Gaafar Nimeiri in 1985.
"We want the army to support us to achieve our goal," Gamereddine added.
Crowds of protesters waved flags, whistled and clapped as darkness fell.
They blame Bashir -- who came to power in a 1989 coup – for a worsening economic crisis.
The protest movement had reached a new peak on Saturday when demonstrators braved volleys of tear gas to reach the military complex, urging the top brass to back them.
Soldiers meanwhile foiled repeated attempts by the feared National Intelligence and Security Service's agents to disperse the demonstrators with tear gas, witnesses said.
On Tuesday the United States, the United Kingdom and Norway for the first time threw their weight behind the protestors, calling for a credible political transition plan in Sudan.
"The time has come for the Sudanese authorities to respond to these popular demands in a serious" way, the diplomatic missions of the three countries said in a joint statement.
"The Sudanese authorities must now respond and deliver a credible plan for this political transition."
Washington had imposed a trade embargo on Sudan in 1997 for Khartoum's alleged links to Islamist groups -- sanctions that were only lifted in October 2017.
The protesters' Saturday move on the sprawling military complex has triggered the largest demonstrations seen yet in the nearly four-month-long movement.
Security agents twice fired tear gas on Tuesday at the protesters in abortive bids to end their sit-in, protest organisers said.
"There was heavy firing of tear gas after which army soldiers opened the gates of the compound for protesters to enter," a witness told AFP.
"A few minutes later a group of soldiers fired gunshots in the air to push back the security forces who were firing tear gas."
A second witness said soldiers had intervened against the security agents.
The demonstrators have called on the army to protect them from the deadly crackdown by riot police and security agents during their four days camped outside its headquarters.
On Tuesday, the crowds could be seen hoisting soldiers into the air on their shoulders, and dancing and chanting with them.
Footage obtained by AFP in Paris showed security agents firing in the air to clear the sit-in on Monday, an operation which had to be abandoned after troops intervened.
Troops can be seen firing machine-guns as protesters run in groups, some taking shelter behind army vehicles and chanting "Allahu Akbar (God is Greatest)".
Late on Tuesday the scene at the army complex was celebratory.
Defence Minister General Awad Ibnouf has vowed the army would prevent any slide into chaos.
"Sudan's armed forces understand the reasons for the demonstrations and is not against the demands and aspirations of the citizens, but it will not allow the country to fall into chaos," Ibnouf said on Monday, according to state media.
The umbrella group spearheading the protests has appealed to the army for talks on forming a transitional government.
Omar el-Digeir, a senior member of the group, said protest organisers had formed a council to open talks aimed at agreeing a "transitional government that represents the wish of the revolution".
Officials say 38 people have died in protest-related violence since December.
But the country's main opposition leader and a key protest organiser Sadiq al-Mahdi said 20 people had been killed by masked men in morning attacks on the sit-in since it began on Saturday.
Bashir, who toppled Mahdi's government in the 1989 coup, is wanted by the International Criminal Court in The Hague on charges of war crimes and genocide connected with the suppression of an ethnic minority rebellion in the western region of Darfur.
He has responded to the demonstrations with tough measures – including imposing a state of emergency – that have seen protesters, opposition leaders, activists and journalists arrested.