Protesters help a fellow demonstrator after he was injured in clashes at Tahrir Square on Tuesday night [REUTERS]

Egyptian security forces have fired tear gas at around 3,000 protesters, some of whom threw stones, in Cairo's Tahrir Square.

The clashes near the interior ministry on Tuesday evening were triggered by family members of the more than 840 people who were killed during the Egyptian uprising in February.

Tahrir Square was the epicentre of the nearly three-week-long uprising that ousted former president Hosni Mubarak.

Al Jazeera's Ayman Mohyeldin reporting from Cairo said at least eight people had been injured.

"Police have been using tear gas to try and disperse the crowd and push them back, " Mohyeldin said. "It is an example of the tension that still exists between the police and ordinary Egyptians."

According to eyewitnesses, protesters at Tahrir Square chanted: "The people demand the fall of the field marshal," a reference to Hussein Tantawi, the head of the Supreme Council of the Armed Forces, which took power when Mubarak stepped down.

Families of those killed are frustrated with what they say is the slow prosecution of security officers believed responsible for the deaths of protesters during the uprising.

Habib al-Adly, Egypt's former interior minister, was sentenced to 12 years in prison on corruption charges in May, but he and other officials are yet to be charged for killing protesters.

Source: Al Jazeera and agencies