LONDON (Reuters) - Iranian forces killed two members of a Sunni Muslim jihadist group in the city of Chabahar on Wednesday and arrested five others, the intelligence minister said, as security forces stepped up measures to prevent militant attacks.

Last week, suicide bombers and gunmen attacked parliament and Ayatollah Khomeini’s mausoleum in Tehran, killing 17 people in what was an unprecedented security breach for Iran.

Islamic State claimed responsibility and threatened more attacks against Iran’s majority Shi’ite population, whom the hardline Sunni militants consider heretics.

Iran has arrested almost 50 people in connection with the attacks.

On Wednesday, state media reported that security forces had fought with members of Ansar al-Furqan, a militant Sunni group, in Chabahar, a city in southeastern Iran.

Intelligence minister Mahmoud Alavi was quoted as saying by state media that two militants had been killed and five arrested. One security officer was also killed, he said.

Local news agencies had earlier said three militants were killed.

“Five members of this terrorist team were Iranians and two were from neighboring countries,” Alavi added.

State news agency IRNA quoted an unnamed source as saying that the militants were planning to carry out attacks this week, during the holy nights of Ramadan.

“The security forces surrounded the house that members of this terrorist cell were based in and launched an attack with backing of the police,” the source said.

Authorities said they had found ammunition, explosive belts and weapons.

Ansar al-Furqan - or Partisans of the Criterion - is a Sunni group based in Sistan and Baluchestan province that has threatened to carry out suicide attacks on economic and military centers in revenge for the government’s execution of Sunni prisoners.

The group, which was formed by the merger of some Sunni Baluch insurgent groups in 2012, is not linked to Islamic State. But it has carried out periodic attacks on military and civilian targets, aiming to highlight what it says is discrimination against Iran’s Sunni ethnic groups.

Iran has stepped up its crackdown against members of such networks in recent years, with mass arrests and death sentences.

The main Sunni Iranian separatist groups increasingly see themselves as part of a larger struggle between Shi’ite Iran and the Sunni-ruled Arab states across the Gulf, which back opposing sides in the Syrian civil war, Iraq and Yemen.

Tehran claims Saudi Arabia is funding most of these groups, a charge Riyadh denies.