About 3,000 Egyptians gathered on Friday in Cairo's Tahrir Square, demanding the prosecution of ousted president Hosni Mubarak and officials of his administration.
The crowd chanted "The people want to try the deposed president" as protesters arrived in the square after Friday prayers.
Activists have dubbed the rally "Day of Trial and Cleansing" to pressure the ruling military council to deliver on promised reforms and bring to justice former regime members.
Protests have been held regularly since Mubarak was toppled on February 11 but the numbers swelled this week after the Muslim Brotherhood - the largest and most organised opposition movement - said it would join Friday's rally.
"Unlike on previous occasions recently, this is a fully representative gathering of Egypt's political movements, including the very powerful Muslim Brotherhood which had stayed away from recent gathering saying they would give the military council more time to meet the people's demands," said Al Jazeera's Mike Hanna, reporting from the square.
"The demands are being made here very clearly, that action needs to be taken against Mubarak and those close to him, that there must be a presidential council established so that the people can express what they want to see as Egypt's future."
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Anger at military
Our correspondent said the crowd was also calling for the immediate resignation of the army chief, following what they see as a lack of action on the part of the military.
"There were very strong orders that if any soldier took part in today's protests he would face immediate court martial.
"We saw a group of five soldiers, at least one of a senior officer, actually join the demonstration and address a portion of the crowd, which was chanting the army and the people are one hand.
Al Jazeera's Hanna said although they were only five soldiers "it is a very significant development given the military's specific instructions".
Former ministers investigated
Several former ministers and members of Mubarak's National Democratic Party are being investigated as part of a sweeping probe into corruption, but pro-democracy activists say key figures still need to be brought to justice.
Former presidential chief of staff Zakariya Azmi was arrested on Thursday, accused of using his powerful position to amass a fortune. He was the highest ranking ex-official to be jailed since Mubarak was toppled on February 11 after 18 days of mass protests.
Many Egyptians consider the prosecutions one of their revolution's key achievements.
Following Mubarak's ouster, state prosecutors arrested three high-ranking officials: interior minister Habib el-Adly, housing minister Ahmed Maghrabi, and tourism minister Zuheir Garana.
Mubarak is under house arrest in the Red Sea resort of Sharm-el-Sheikh.
Source: Al Jazeera, agencies