By Peter Martell
BBC News, Khartoum
Mr Bashir's supporters thronged the streets of Khartoum
Thousands of protesters poured out in the streets of Sudan's capital, Khartoum, just minutes after an arrest warrant was issued for President Omar al-Bashir.
Many directed their anger towards the prosecutor of the International Criminal Court (ICC), Luis Moreno-Ocampo.
"This Ocampo is crazy if he thinks he will take our president," said protester Ahmed Fanous, carrying a placard of the lawyer defaced with a cross.
"He is a tool of the West to attack Sudan."
The ICC issued an arrest warrant on Wednesday for Mr Bashir for war crimes and crimes against humanity.
Mr Bashir, who denies the charges, has already dismissed a warrant as being "not worth the ink" in which it is written.
The warrant was long expected, and protesters quickly took to the streets as the news broke.
'Treachery' of ICC
Busloads of furious demonstrators arrived to a rally at a government building in the downtown area of Khartoum, singing and banging drums.
Some came direct from government offices to join an organised rally, but others said they had joined the demonstrations spontaneously.
Many carried giant posters of the president in support.
"Down to America, down to the UN," one group of women chanted.
"We will support President Bashir until we die," screamed another.
Others warned that the warrant would have a negative impact to Sudan.
"This will bring trouble to our country - this court should not be doing this," said teacher Mohammed Hussein, shaking his head.
Another pointed to a series of posters of Mr Bashir recently erected around the capital, praising the president's "virtues" and criticising the "treachery" of the world court.
"This man is our leader, so do they really think we would allow anyone to come and put him in prison?" asked another demonstrator, Abubaker Omar.
"Why do they do this to Sudan, and never to the leaders of America?" he added.
Larger demonstrations are expected in coming days, and security has been increased around foreign embassies or United Nations offices. The government have vowed to protect foreigners.
But not all support Mr Bashir - especially those Sudanese from areas affected by the long years of fighting with Khartoum such as Darfur, the east or the south.
However, people said they feared reprisals if they spoke out now to support the arrest warrant.
"He must face justice for what he has done," said a Darfuri now living in Khartoum, who asked not to be named.
"But I don't think this [warrant] is going to change anything for us. If anything it could make things worse."
According to the United Nations, some 300,000 have died in Darfur since the conflict erupted in 2003 and more than two million have been displaced - figures strongly rejected by Khartoum.
Others said they were concerned at what the warrant could mean for wider stability in Sudan.
"We are nervous of what will happen next," said Nhial Deng, from the semi-autonomous south of Sudan, which signed a peace deal with Khartoum to end the civil war there four years ago.
"We are worried about how this will affect the peace in the south, and in all the country."