The field marshal, who was Hosni Mubarak's defense minister for two decades, is head of the ruling army council that took control when the former president was ousted by a popular uprising in February.

State-run television and a state-run newspaper said Tantawi made the surprise visit to review the flow of traffic in the square, a major road hub in central Cairo which had been closed to vehicles during the protest until this weekend.

Protesters, who have erected tents on traffic islands, said they were not aware of any visit by officials. Wall graffiti and banners in and around the square have demanded an immediate end to military rule, with some calling for Tantawi to go.

After protesters clashed with police in streets close to the Interior Ministry near the square last month, the field marshal announced that presidential elections would be set for June 2012, sooner than an army timetable previously envisaged.