Police are using tear gas to disperse thousands of demonstrators in the Sudanese capital protesting the rule of autocratic President Omar al-Bashir.

The Friday protests took place in at least eight different districts in Khartoum, including the capital's twin city of Omdurman, where supporters of opposition leader Sadeq al-Mahdi took to the streets after noon prayers.

There were also protests in the railway city of Atbara, a traditional bastion of dissent and one of several cities where anti-government demonstrations began Dec. 19, initially over rising prices and shortages but which quickly shifted to calls for al-Bashir to step down.

At least 40 people are reported to have been killed in the protests.

Al-Bashir has been in power since 1989 when he led a military coup that toppled an elected government.