Representatives of Iraq's main ethnic groups have concluded three days of talks in Finland, where they studied the reconciliation process in other countries.

Organizers of the event, which ended Sunday, said it brought together Shi'ite and Sunni Arabs as well as Kurds with a goal of ending the violence in Iraq.

The Helsinki-based Crisis Management Institute issued a statement saying the conferees adopted a set of principles for joint national action. It said the Iraqis will meet again in Baghdad within three months.

The 36 participants, which included several prominent Iraqi politicians, met with advisers from Northern Ireland and South Africa -- two countries with recent experience in reconciliation.

Back in Iraq, hard-line Shiite cleric Moqtada al-Sadr rejected conditions set by Iraqi Prime Minister Nouri al-Maliki to end the fighting between his militia and Iraqi security forces. A spokesman for the Sadr movement accused Maliki of wanting to resolve the problem by force and not dialogue.

Last week, Maliki set four conditions for stopping the military crackdown on Mahdi Army militia. The prime minister called on militants to hand over weapons and stop interfering in politics. He also demanded that they hand over all fighters wanted by the government.

Militias loyal to Sadr have been battling coalition and Iraqi forces in Baghdad's Sadr City district since late March. More than 300 people have been killed in those clashes.

Separately, insurgents fired a volley of rockets or mortar rounds into the city's Green Zone during a heavy sandstorm on Sunday. At least eight rounds hit the heavily guarded area, which houses the Iraqi government and the U.S. embassy. There were no reports of damage or casualties.