Tehran - A suicide attack Wednesday on a Revolutionary Guards bus in southeastern Iran killed at least 20 people and left 20 more wounded, the official news agency IRNA reported.
"The suicide attack on an Islamic Revolutionary Guards Corps personnel bus happened on the Khash-Zahedan road," IRNA said.
"This terrorist act happened a short time ago and according to reports at least 20 have been martyred and 20 have been wounded," an informed source told IRNA.
A picture released by the Fars news agency showed a hulk of twisted metal lying by the side of a road, unrecognisable as a bus.
The Guards issued a statement confirming the attack. It said the troops were returning from the border.
"In this suicide attack a car filled with explosives blew up besides a bus carrying a unit of the Guards ground forces causing the martyrdom and wounding of a number of the protectors of our Islamic homeland's border."
The attack took place in the volatile southeastern province of Sistan-Baluchistan which has a large, mainly Sunni Muslim ethnic Baluchi community straddling the border with Pakistan.
Fars said the attack was claimed by Jaish al-Adl, a jihadist group formed in 2012 as a successor to the Sunni extremist group Jundallah (Soldiers of God), which waged a deadly insurgency against Iranian targets over the past decade.
The Jaish al-Adl "has issued a statement officially taking responsibility for the terrorist attack," Fars reported. The group is blacklisted as a "terrorist group" in Iran.
The attack came on the same day as the United States gathered some 60 countries in Poland for a conference on the Middle East and Iran which they hoped would increase pressure on Tehran.
Dubbing the meeting in Poland the "WarsawCircus", Iranian Foreign Minister Mohammad Javad Zarif said it was "no coincidence that Iran is hit by terror on the very day" that the talks began in the Polish capital.
"Especially when cohorts of same terrorists cheer it from Warsaw streets & support it with twitter bots? US seems to always make the same wrong choices, but expect different results," Zarif wrote on Twitter.
- 'US obsession' -
He earlier blasted the two-day conference being co-hosted by Washington in Warsaw as "dead on arrival".
"It is another attempt by the United States to pursue an obsession with Iran that is not well-founded," Zarif told a Tehran news conference.
Sistan-Baluchistan has been the scene of other attacks.
On January 29 three members of an Iranian bomb squad sent to the scene of an explosion in its capital Zahedan were wounded when a second device blew up as they were trying to defuse it, police said at the time.
And in early December last year two people were killed and around 40 others wounded in the port city of Chabahar, also in Sistan-Baluchistan, in an attack which Zarif at the time blamed on "foreign-backed terrorists" -- a reference to Sunni Muslim extremists.
The bloodiest attack in recent times to have hit Iran took place in September when assailants killed 24 people at a military parade in the southwestern city of Ahvaz.
In July at least 10 members of the Revolutionary Guards were killed when insurgents attacked one of their bases along the border with Iraq.AFP