Iranian President Hassan Rouhani has accused the United States and Israel for a suicide bombing that targeted its elite paramilitary Revolutionary Guard force in the country's southeast on Wednesday, killing at least 27 members.
The Iranian leader said that Israel's "regional agents" were to blame for the attack, without identifying any other states from the Middle East.
The force said on Wednesday a suicide bomber driving a vehicle laden with explosives attacked a bus transporting members of the Guard in the province of Sistan-Balochistan.
A militant group, Jaish al Adl (Army of Justice), which says it seeks greater rights and better living conditions for the ethnic minority Balochis, has claimed responsibility for the attack, Iranian media have reported.
"The crime will remain as a 'dirty stain' in the black record of the main supporters of terrorism in the White House, Tel Aviv and their regional agents," Mr Rouhani said.
Iran does not recognise Israel, which is a key US ally in the region and sees Tehran as posing an existential threat to its existence.
In the past, Tehran has accused its main regional rival Saudi Arabia of backing militia groups who have carried out bloody attacks against Iranian security forces. Riyadh has denied the charges.
Repeating warnings made by senior commanders of the Guards, Mr Rouhani said Iran was determined to bring justice to those responsible for one of the worst assaults against the Revolutionary Guards in years.
The assault, which wounded at least 13 people, took place in the province of Sistan-Balochistan, which has a large ethnic Balochi community, which straddles the border with Pakistan.
Jaish Al Adl has carried out attacks against the border guards from Pakistan since its founding in 2012.
Iran has called on neighbouring countries to crack down on separatist groups.
