Thousands of protesters have gathered in Cairo's Tahrir Square to demand the resignation of Egypt's Islamist-backed President Muhammad Morsi and new elections.
Protesters waved Egyptian flags and chanted "Leave, Morsi!"
"We are now at a point where it's either us or them," anti-Morsi protester Alia Khaled told Reuters. "If people give up too easily today, then everyone will go home and it would be as if nothing had happened. And we can't let our country slip away."
On the other side of the city, thousands of Morsi supporters staged a rival rally near the presidential palace. Morsi supporters have vowed to defend the presidential palace if it is attacked by anti-Morsi crowds.
Some of his supporters wore homemade body armor and carried shields and clubs, saying that was a precautionary measure against possible violence.
Egypt’s powerful military has warned it is ready to intervene to control any major unrest.
June 30 marks the one-year anniversary of Morsi taking office as Egypt’s first democratically elected president.
The protest movement says it has collected 22 million signatures of people who want Morsi to resign.
The opposition says Morsi has squandered the opportunity to implement democratic reforms and has instead handed power to the Muslim Brotherhood.
Egypt’s economy has been struggling and inflation soared since Morsi took office last year. The country’s vital tourism sector has been hit especially hard.
On June 29, at least eight lawmakers resigned from the Islamist-dominated parliament to protest Morsi’s policies.
Morsi has already vowed he has no intention of resigning. The president's supporters accuse the opposition of using undemocratic means to force change.
Eight people, including an American, have been reported killed during violence across Egypt in the past week.
Based on reporting by AP, AFP, and Reuters