|Protesters swarmed a police van in Cairo's Tahrir Square after pleting the vehicle with rocks and sticks [Asad Hashim]
Clashes between police and protesters in Cairo have left dozens wounded and have so far led to the arrest of at least four demonstrators.
The arrests on Saturday followed the deployment of riot police into the Egyptian capital's Tahrir Square to disperse a sit-in of about 500 people who remained camped in the place after a mass protest rally a day earlier.
Initial reports from Egypt's interior ministry said at least four protesters had been arrested, but the number could be higher.
Witnesses said riot police entered the square early on Saturday, dismantling tents and forcibly removing some protesters.
The ruling military government tolerates daytime demonstrations in the central square, a symbol of the country's January uprising that deposed former-president Hosni Mubarak, but claims that long-term occupation paralyzes the city.
Police with batons charged at least one group of activists, and several journalists were reportedly wounded in the ensuing clash.
Later in the morning, protesters attacked a riot police van parked in the area, pelting the vehicle with rocks and sticks, breaking its windows and forcing their way inside before driving the van into the square.
Protesters were chanting anti-security slogans including, "Riot Police are Thugs and Thieves" and "Down with the Marshal" - referring to Field Marshal Hussein Tantawi, Egypt's military ruler.
Stubborn protesters played cat-and-mouse with riot police as they were chased outside of the square and into side streets.
"We are using side streets to pretend to run errands, but we are just regrouping and going back," said Sahar Abdel-Mohsen, who joined in the protest after a call went out on Twitter telling people to come down to Tahrir.
The clashes come a day after tens of thousands of people filled Tahrir Square to participate in the "Friday of One Demand". The protest was meant to pressure the ruling military council to transfer power to a civilian government.
Most of the political groups that took part in Friday’s rally opted not to stage a sit-in in Tahrir following the protest. A number of protesters, mainly the victims and relatives of victims of violence during the country’s uprising, decided to remain in the square overnight.
With additional reporting by Asad Hashim