Social media users saw the refusal to sing as a show of support for the eight-week-old protests, one of the biggest challenges to Iran's clerical leaders since the 1979 Islamic Revolution.

The bloody crackdown by the police and the deadly fire, whose origins are disputed, have shaken a society already on edge after a month of violence involving security forces and anti-government protesters.

The 2000 tonne ammonium nitrate explosion on Tuesday killed 158 people and injured more than 6,000, compounding months of political and economic collapse

The timing of the announcement suggests that Tehran could harden its position in a standoff with Western powers which has raised fears of a direct military confrontation.

The allegation will likely ratchet up tensions with Iran's rival Saudi Arabia and its Gulf allies, which along with the United States have been working to isolate the Islamic Republic.

Despite the army commander's claim that the police have quelled the unrest, the situation remains difficult to ascertain due to Iran's vastness and restrictions on social media.

Thirteen people have been killed and hundreds arrested, according to officials and social media.

The ISIS leader has frequently been reported killed or wounded since he declared a caliphate from the pulpit of a mosque in Mosul in 2014.

Amar Hussein, drawn to jihad by his local mosque preacher, joined al Qaeda when he was just 14. He now awaits legal proceedings as a member of ISIS.

A soldier said that he wanted citizens to know the price for supporting terrorists while another man thought that everyone's entitled to a burial.

Every time Iraqi forces capture a section of Mosul in their offensive against ISIS, it can take up to a week to ensure it is clear of militants.

Egypt is confident of luring back millions of foreign visitors, according to its new tourism minister, despite heavy first quarter losses and setbacks, including a bomb that brought down a Russian passenger plane in the Sinai.