KHARTOUM (Reuters) - Hundreds of protesters hit the streets in several neighborhoods of Sudan’s capital Khartoum on Thursday and security forces rounded up a number of demonstrators calling on President Omar al-Bashir to step down, witnesses said.

FILE PHOTO: President Omar al-Bashir of Sudan delivers a speech at the Presidential Palace in Khartoum, Sudan, February 22, 2019. REUTERS/Mohamed Nureldin Abdallah/File Photo

It was the latest in a series of protests against Bashir and his National Congress Party across Sudan since Dec. 19. It is the most sustained popular challenge to Bashir since he took power in a military coup 30 years ago.

Witnesses said that activists chose a women’s day theme for Thursday’s protests and many of the hundreds who turned out in Omdurman, across the Nile river from the center of the capital, and in eastern Khartoum, were female.

They chanted “Peace, freedom and justice”, and “Revolution is the choice of the people”. Hundreds also took to the streets in Khartoum’s Burri neighborhood, a flashpoint for protests.

Security forces appeared to have changed tactics and were rounding up protesters using batons, and sending them to trial in emergency courts, rather than dispersing them with tear gas, according to witnesses.

However, tear gas was used to scatter demonstrators at the National University, a witness said, and later in Burri.

A police spokesman could not immediately be reached for comment.

Officials have confirmed 33 deaths in the unrest since December, though activists say the toll is significantly higher.

Last month Bashir declared a state of emergency, dissolved the central government, replaced state governors with security officials, expanded police powers and banned unlicensed public gatherings.

Emergency courts have since been trying protesters in evening sessions, sparking further rallies outside court buildings.

On Tuesday, a strike called by opposition activists shut down some non-essential health services and economic activity in Khartoum.