Iran said Tuesday it had seized explosives destined for an attack on one of its holy cities and that more than 130 members of militant extremist groups had been arrested.
The disclosures by Intelligence Minister Mahmoud Alavi lay bare the threat posed to Shiite Iran by Sunni jihadists such as the Islamic State (IS) group fighting in Iraq, near the Iranian border, and in Syria.
Two explosive belts were among lethal ordnance recovered ahead of Quds (Jerusalem) Day, a July 25 memorial on the last Friday before the end of the Muslim holy fasting month of Ramadan, Alavi said.
"Significant quantities of explosives that were to be used in a holy city in the country were neutralised," he told members of parliament, according to the ISNA news agency.
Alavi did not specify over what period the "Takfiris" -- a term used to describe Sunni militants in groups such as IS or Al-Nusra Front, Al-Qaeda's Syrian affiliate -- had been arrested.
However, the explosive belts were meant for use in two Iranian provinces, ISNA quoted him as saying.
Iran, which is 90 percent Shiite, supports President Bashar al-Assad in Syria and was the first country to send military advisers and arms to Iraq when it was hit by a jihadist surge from IS this summer.
The IS group has been accused of carrying out widespread atrocities, including mass executions, abductions, torture and forcing women into slavery.
The militant group, which is fighting for more territory in Iraq and Syria despite air strikes from the United States and other western and Arab countries, is also threatening other states.
Turkey last week won parliamentary approval for military intervention against IS in Syria and Iraq, but it has yet to announce any plans for military action despite the jihadists advancing to its doorstep.
After first launching strikes against IS in Iraq in August, the United States has built a coalition to wage a broader air campaign.
Iran is not in the coalition, but has separately aided the Baghdad government by providing military advice and weaponry.
On Monday, officials said the US military had started flying attack helicopters against the jihadists in Iraq for the first time, marking an escalation in the air war that puts American troops at higher risk.
In all, nearly 2,000 air raids have been launched by the coalition in both Iraq and Syria, US defence officials said.