Organizers behind anti-government demonstrations in Sudan say security forces have killed at least five protesters in the last twenty-four hours.

Saturday witnessed one of the largest turnouts in more than three months of protests calling on President Omar al-Bashir to resign.

Sarah Abdel-Jaleel, a spokeswoman for the Sudanese Professionals Association, told The Associated Press on Sunday that four people were killed in the capital city of Khartoum when security forces tried to disperse crowds approaching the military's headquarters.

Abdel-Jaleel says another protester was killed in the neighboring city of Omdurman.

The state-run SUNA news agency has quoted police spokesman General Hashim Abdel-Rahim as saying that one person was killed "during disturbances in Omdurman."

International rights groups say at least 60 people have been killed since protests began.