Iran yesterday warned neighbouring Pakistan it would "pay a heavy price" for allegedly harbouring militants who killed 27 of its elite Revolutionary Guards in a suicide bombing near the border earlier this week, state television reported.
Revolutionary Guards chief Major General Mohammad Ali Jafari also accused Tehran's regional rival Saudi Arabia and the United Arab Emirates of supporting militant Sunni groups that attack Iranian forces, saying they could face "reprisal operations."
Pakistan, Saudi Arabia and the UAE deny backing such militants.
"Why do Pakistan's army and security body ... give refuge to these anti-revolutionary groups? Pakistan will no doubt pay a high price," Jafari said in remarks live on state television.
Jafari was addressing a large crowd gathered for the funeral of the victims of Wednesday's suicide bombing, which took place in a southeastern region where security forces are facing a rise in attacks by militants from the country's Sunni Muslim minority.
The Sunni group Jaish al Adl (Army of Justice), which says it seeks greater rights and better living conditions for the ethnic minority Baluchis, claimed responsibility for the attack.
Iran says militant groups operate from safe havens in Pakistan and have repeatedly called on the neighbouring country to crack down on them.
Jafari's remarks came amid heightening regional tensions after Israel and the Gulf Arab states attended a summit in the Polish capital Warsaw this week where the United States hoped to ratchet up pressure against Iran.