One person has died in unrest in the Iraqi Kurdish town of Halabja, as hundreds of angry residents attacked a memorial for victims of Saddam Hussein.
Protesters tried to storm the monument before troops fired
Police opened fire as an event marking the 18th anniversary of the Halabja gas attack was disrupted by protesters.
Witnesses said a 14-year-old boy died and eight people were hurt.
Residents of the impoverished town were demanding better local services and compensation for victims of the attack, in which about 5,000 people died.
Demonstrators had blocked roads to prevent access to Kurdish politicians, who correspondents say are accused of cynically exploiting the annual ceremony while doing little to help local people during the rest of the year.
"We've had enough of these liars and we don't want to see them in our town," said Rizin Walid, a university student.
A museum dedicated to the victims of the attack - blamed on Saddam Hussein's forces during the Iran-Iraq war - was burnt down.
The demonstrators badly damaged the inside of the 30m (90-foot) monument by setting fire to it, although the exterior was undamaged.
One report says demonstrators swarmed onto the memorial site and removed hundreds of photographs of their loved ones before the destruction began.
Feelings against the Baghdad government and autonomous Kurdish leaders have been running high in the town and the protests had been planned for several days.
"They did not do anything for us.
The 30m-high Halabja monument was engulfed in smoke
"Until now, the government did not compensate us," said one man who lost his father in the 1988 attack.
"We burned this building because the local officials are making a lot of money from international organisations due to the attack against our town and pocketing it, we don't see a penny of that money," said another demonstrator.
Earlier, Iraqi President Jalal Talabani, who is Kurdish, called on Iraqis to strive for unity.
"The Halabja tragedy and the massacres that followed remind us of the need to strengthen our unity in the face of efforts by supporters of the former regime and by terrorists to restore dictatorship," he said.
The gassing of the Kurds of Halabja is one of several criminal cases for which Saddam Hussein may be tried after the first stage of his trial for the Dujail massacre of Shia Muslims.