Tehran: The “formal incitement against the UAE from within Iran is unfortunate, and has escalated after the Ahvaz attack,” UAE Minister of State for Foreign Affairs Dr. Anwar Gargash tweeted.

His words followed comments by Iranian officials alluding to the involvement of Gulf states in the training of militants who attacked a military parade that killed 25 people and wounded nearly 70. 

“The UAE’s historical position against terrorism and violence is clear and Tehran’s allegations are baseless,” Gargash said.

Iranian President Hassan Rouhani did not identify those behind Saturday’s attack, which was claimed by an Arab separatist group.

“It is Americans who instigate them and provide them with necessary means to commit these crimes,” Rouhani said.

Saturday’s attack, in which militants disguised as soldiers opened fire on an annual Iranian military parade in Ahvaz, in the oil-rich southwest, was the deadliest attack in the country in nearly a decade.

Women and children scattered along with once-marching Revolutionary Guard soldiers as heavy gunfire rang out, the chaos captured live on state television.

Diplomats summoned

The region’s Arab separatists, once only known for night-time attacks on unguarded oil pipelines, claimed responsibility for the assault, and Iranian officials appeared to believe the claim. 

Iran summoned diplomats from Britain, Denmark and the Netherlands early on Sunday for allegedly harbouring “members of the terrorist group” that launched the attack.

Iranian Foreign Minister Mohammad Javad Zarif had earlier blamed regional countries and their “US masters” for funding and arming the separatists, issuing a stark warning as regional tensions remain high in the wake of the US withdrawal from the Iranian nuclear deal.

US condemns attack

The parade was one of many around the country marking the start of Iran’s long 1980s war with Iraq, commemorations known as the "Sacred Defence Week."

State TV reported hours later that all four gunmen had been killed.

At least eight of the dead served in the Revolutionary Guard, an elite paramilitary unit that answers only to Iran’s supreme leader.

The Guard responded to the attack Sunday, warning it would seek “deadly and unforgiving revenge in the near future.”

Tensions have been on the rise since the Trump administration pulled out of the 2015 nuclear accord and began restoring sanctions that were eased under the deal.

It also has steadily ramped up pressure on Iran to try to get it to stop what Washington calls its “malign activities” in the region.

The US government nevertheless strongly condemned Saturday’s attack, saying it “condemns all acts of terrorism and the loss of any innocent lives.”

Initially, authorities described the assailants as “takfiri gunmen,” a term previously used to describe the Daesh. Iran has been deeply involved in the fight against Daesh in Iraq and has aided Syrian President Bashar Al Assad in his country’s civil war.

But later, state media and government officials seemed to come to the consensus that Arab separatists in the region were responsible.

The separatists accuse Iran’s Persian-dominated government of discriminating against its ethnic Arab minority. Khuzestan province also has seen recent protests over Iran’s nationwide drought, as well as economic protests.

Iran has blamed Saudi Arabia for funding Arab separatists

Early Sunday, a Foreign Ministry statement similarly criticised Britain and said Danish and Dutch diplomats were told Iran “already warned” their governments about harbouring Arab separatists.

Yacoub Hor Al Tostari, a spokesman for the Arab Struggle Movement to Liberate Ahvaz, told The Associated Press that members of an umbrella group of Ahvazi activists his organisation leads carried out the attack.

The attack undermined the Iranian government “on the day it wants to give a message to the world that it is powerful and in control,” Al Tostari said. To bolster his claim, he gave details about one of the attackers that the AP could not immediately verify.

Daesh also claimed responsibility for the attack, but provided no evidence it carried out the assault. They also initially wrongly said the attack targeted Rouhani, who was in Tehran at the time. The militants have made a string of false claims in the wake of major defeats in Iraq and Syria.

In the last decade, mass-casualty militant attacks have been incredibly rare. In 2009, more than 40 people, including six Guard commanders, were killed in a suicide attack by Sunni extremists in Iran’s Sistan and Baluchistan province.