Some 35 people were wounded, 15 critically, in the blast in the city of Mahabad, in a predominantly Kurdish area near the borders of Iraq and Turkey, the ISNA news agency reported.
There was no immediate claim of responsibility, but local officials blamed militants, possibly helped by foreign countries wishing to harm the Islamic Republic during Sacred Defence celebrations, an annual ceremony for the Iranian military.
This bomb was a time-bomb planted on a tree among the people and it went off at 10:20 (0650 GMT), the website of state-run television IRIB quoted a military official as saying.
Counter-revolutionary groups, by inserting themselves among the people attending the armed forces parade, showed their heinous face, said Vahid Jalalzadeh, the provincial governor of Irans West Azerbaijan province.
Television footage showed troops marching past a ceremonial podium when a blast happened. Pictures of the aftermath showed blood on the ground, shoes and an abandoned pram.
Ahmadinejad away
The attack occurred as President Mahmoud Ahmadinejad was attending the United Nations General Assembly in New York amid a standoff between Tehran and major powers over Irans nuclear programme, which the West suspects is aimed at making weapons.
On Aug 4, a homemade explosive went off near Ahmadinejads motorcade as he was travelling to the western city of Hamadan. He was unharmed and officials said the blast was just a firecracker.
Several armed groups hostile to the government are active in Iran, including Kurdish separatists in the northwest and Baluch militants in the southeast. The Sunni Muslim Jundollah Baluch militant group, which Iran says has linked to al-Qaeda, is the most active. It claimed a double suicide attack that killed 28 people, including Revolutionary Guards, on July 15 in revenge for the execution of its leader.
Wednesdays explosion happened some 50 metres from the podium and two officials wives were among the dead.
