Army tanks sealed off the Qasr al-Nile Bridge from the Cairo Opera House's side to prevent a pro-Mursi march from accessing Tahrir Square, the Middle East News Agency reported on Friday.
A march of former president Mohamed Mursi's supporters tried to reach the square via Qasr al-Nile Bridge, the agency added.
The march headed to October 6th Bridge after they were unable to get to the square using Qasr al-Nile Bridge.
People in Tahrir Square are on alert as they prepare to counter the pro-Mursi march.
Several army vehicles and armed soldiers are present at the square, and three helicopters are circling overhead.