Iran says it has killed mastermind of twin attacks

While ISIS claimed responsibility, Iranian officials have also suggested Saudi Arabia may have played a role - and Iran's foreign minister called the official USA response "repugnant", after President Trump ended his expression of condolences for the victims with the message that "states that sponsor terrorism risk falling victim to the evil they promote". Riyadh has denied involvement in the suicide bombings and gun attacks on Iran's parliament and the mausoleum of the Islamic Republic's founder, Ayatollah Ruhollah Khomeini.

The ayatollah made the statement in remarks of condolence for the victims.

The Iranian leader has accused the United States and its regional ally Saudi Arabia of funding hardline Sunni militants, including Islamic State, which carried out its first attack in Iran on Wednesday in Tehran, killing 17 people.

Yet, at the funeral following Friday prayers, mourners chanted, "Down with the USA", and they called for death for members of the Saudi royal family. Officials have reported the arrests of suspected IS members in and around Tehran, as well as in the country's centre, southern governorates, and western provinces near the Iraqi border. Iranian President Hassan Rouhani, who favours opening up to the world, has condemned the attacks, without pointing a finger at any country.

As the Tehran Times reports, "Iran has been helping the governments in neighboring Iraq and Syria in fight against Daesh, which considers Shiites to be apostates".

US intelligence called the incident the worst domestic terror attack in Tehran since the 1980s, but an official said there had been signs IS was at least hoping to strike.