The "Islamic State of Iraq and Syria" (ISIS) on Wednesday (September 26th) threatened to carry out new attacks in Iran, days after it claimed a deadly shooting at a military parade in the country's southwest, AFP reported.

Iran is "flimsier than a spider's web, and with God's help, what comes will be worse and more bitter", the group said in a statement on the Telegram messaging app.

Iranian authorities have blamed "jihadist separatists" for the assault Saturday in the southwestern city of Ahvaz, which killed 24 people including a four-year-old child and other civilians.

The attack targeted a parade in Khuzestan province, commemorating the 1980-1988 Iran-Iraq war.

The border region, home to a large ethnic Arab community, was a major battleground of the conflict and saw ethnic unrest in 2005 and 2011.

Iranian officials initially blamed Arab separatists, who they claimed were behind previous unrest, for the attack, saying they were backed by some Gulf countries.

This version was bolstered when a movement called "Ahwaz National Resistance", an Arab separatist group, claimed responsibility shortly after the assault.

But ISIS was also quick to claim responsibility and later posted a video of men it said were the attackers.

In a three-minute audio recording released Wednesday, the extremist group's spokesman Abu Hassan al-Muhajir said Iran "had not recovered from the fearful shock, which God willing will not be the last".

On June 7th, 2017 in Tehran, 17 people were killed and dozens wounded in simultaneous attacks on the parliament and on the tomb of revolutionary leader Ayatollah Ruhollah Khomeini -- the first inside Iran claimed by ISIS.