Ali Hassan al-Majid, an Iraqi defense minister under the former Baathist regime, was executed in January 2010 for ordering chemical weapons attacks on the Kurdish population in 1988. An estimated 5,000 people were killed during the assault, earning Majid the nickname Chemical Ali.
Iraqi lawmakers are said to be considering a measure that would honor the Kurdish victims as martyrs during a popular uprising.
Iraqi Prime Minister Nouri al-Maliki said in a statement marking the anniversary that memories of the attack are a deterrent against the return to a dictatorship.
"On this painful occasion, I present my warm condolences for the people of Halabja, the Kurdish people and the whole people of Iraq, requesting Allah almighty to bless our country with security, stability and avoid confronting them for any suffering," the Voices of Iraq news agency quoted the prime minister as saying.
An Iraqi supreme court in March 2010 recognized chemical weapons attacks on Halabja as an act of genocide.