Clashes between Iraqi protesters and security forces in central Baghdad killed at least two demonstrators overnight, security and medical sources said on Monday.
It was the first such deadly incident for months at Tahrir Square, which became a symbol of anti-government protests during months of mass unrest last year.
The protesters had begun marching from Tahrir to nearby Tayaran Square chanting about worsening power cuts during a heatwave that has sent temperatures soaring above 50 Celsius (122 Fahrenheit).
Security forces tried to contain the march and fired tear gas, according to police, medics and protesters. The protesters threw stones and petrol bombs, a security source said.
Two protesters who were at the demonstration, and Ali Bayati, a member of Iraq's semi-official High Commission for Human Rights, said security forces had fired live ammunition to disperse the crowd.