KHARTOUM (Reuters) - A Sudanese policeman has died from his wounds after protesters threw stones at a police vehicle passing close to demonstrations in the capital Khartoum, a police spokesman said on Friday.

The vehicle was passing the area by chance late on Thursday, the spokesman said, adding that a number of suspects had been arrested.

The case brings the official death toll during protests that have spread since Dec. 19 across Sudan to 32, including three security personnel. An opposition-linked doctors’ syndicate said last week that 57 people had been killed in the protests.

“The vehicle was pelted with stones, and they were police returning from training and had no link to the dispersal of the unrest,” said police spokesman Hashem Ali.

Security forces dispersed protests close to the presidential palace in Khartoum on Thursday, rounding up several dozen of them and driving them away in pick up trucks, witnesses said.

On Friday police fired teargas to disperse hundreds of people who protested after leaving a mosque in Omdurman, across the Nile from central Khartoum, witnesses said.

The protesters had blocked a road with stones and branches chanting, “Down, that’s it!”, “Freedom, peace and justice”, and “The people’s choice is revolution”.

The protests were triggered by a deepening economic crisis and have become the most sustained popular challenge to President Omar al-Bashir since he took power in a coup nearly 30 years ago.

The president and his ruling National Congress Party have shown no sign of bowing to demands to quit and have blamed the unrest on unnamed foreign agents.