Iran thwarts 'major terror plot'

The intelligence ministry had discovered and foiled "one of the biggest takfiri-Wahhabi terrorist plots," official IRNA news agency confirmed, using terms used to describe groups that adopt the extremist Saudi theology.

"A series of bomb attacks prepared in various areas deep inside the country and especially in Tehran and some other provinces... were foiled, the terrorists were arrested and a number of ready-made bombs were recovered," it said, without providing any further detail.

However, the plot included plans for "suicide attacks in Tehran", Ali Shamkhani, secretary of Iran's Supreme National Council suggested.

Suspects detained during investigations "both inside and outside the country" were under interrogation by intelligence authorities.

Last week, 12 Kurdish rebels died when clashes erupted between Iranian forces and members of the Party of Free Life of Kurdistan (PJAK) - an Iranian Kurdish group with close links to Turkey's outlawed Kurdistan Workers' Party (PKK) - on the country's northwestern and southeastern borders .

On the same day, a police officer and five members of the militant Jaish-ul-Adl group were killed in unrelated clashes in the Baluchistan province.

But despite its activity across the region, Iran has faced relatively little threats from militants due to powerful security measures established along its borders.

Last year, General Ahmad Reza Pourdastan, the Iranian army's head of ground forces, announced a 40 kilometre (25 mile) limit on the borders with Iraq and Afghanistan, which if breached would trigger action.

"Before the enemy reaches the borders, its actions will be neutralised," he affirmed.

Meanwhile in Tehran, an increased police presence across the capital in November and December raised concerns among locals who believed an attack was imminent.

But Tehran's police chief, Hossein Sajedinia said the presence of armed security forces at subway stations and other public areas in Tehran was part of "counter-terrorism drills".

Iran - the region's predominant Shia powerhouse - has been heavily involved in battles against the Islamic State groups both in Iraq and Syria - while being accused of "infiltrating" rebel groups in Yemen and Bahrain in a bid to "boost its influence" across the Arab world.